Patent Publication Number: US-10330447-B2

Title: Projectile with core-locking features and method of manufacturing

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/532,069 titled PROJECTILE WITH CORE-LOCKING FEATURES AND METHOD OF MANUFACTURING THE PROJECTILE, and filed on Jul. 13, 2017, the contents of which are incorporated herein by reference in its entirety 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to firearm ammunition, and more particularly to an expanding projectile with features to retain the core together with the jacket on impact with a target and a method of manufacturing the same. 
     BACKGROUND 
     Firearms, such as rifles and pistols, can be used for hunting, law enforcement, and self-defense. A firearm is configured to fire or otherwise launch a projectile (e.g., a bullet) towards a target or object located within an area. The projectile is designed to travel through the air and impact the target located a distance away from a shooter&#39;s position. Before firing, the projectile is held in the mouth of a cartridge casing that contains a propellant (e.g., gunpowder) and includes a primer. Upon activating a trigger assembly of the firearm, a firing pin of the firearm strikes the primer to ignite the propellant and launch the projectile through the barrel of the firearm. With respect to game-hunting, one goal of the projectile is to expand or mushroom on impact while retaining the core within its jacket. 
     SUMMARY OF THE DISCLOSURE 
     Embodiments of the present disclosure relate generally to an expanding or mushrooming projectile having a malleable core disposed within a jacket formed from a malleable material. Embodiments of the present disclosure also relate to a method of making an expanding projectile. 
     One aspect of the present disclosure is directed to an expanding firearm projectile comprising a malleable core and a jacket. In one embodiment, a firearm projectile has a core extending along a central axis from a base portion to a tip portion, the base portion generally having a cylindrical shape and the tip portion comprising an ogive shape. A jacket encases the core along the base portion and the tip portion, the jacket having a shank portion defining a closed rear end and an ogive portion extending to an open front end. A plurality of protrusions extends into the core from an inside of the shank portion, the plurality of protrusions having a spaced-apart arrangement with each of the plurality of protrusions engaging the core to retain the core together with the jacket upon impact with a target. 
     In some embodiments, the shank portion has a rear sidewall portion with a rear sidewall thickness and a forward sidewall portion with a forward sidewall thickness less than the rear sidewall thickness. For example, the rear sidewall thickness is from 1.5 to 3.0 times the forward sidewall thickness, including 2.0, 2.25, 2.5, and 2.75 times the forward sidewall thickness. In some such embodiments, each of the protrusions extends from the shank portion between the rear sidewall portion and the forward sidewall portion. 
     In some embodiments, the core comprises a first metal and the jacket comprises a second metal, the first material being more malleable than the second metal. Examples of metals for the core include lead, a lead alloy, a lead-antimony alloy, tin, and a tin alloy. Examples of jacket metal include copper, brass, and gilding metals. In one embodiment, the core comprises a lead-antimony alloy containing antimony in an amount from 0.25 percent to 6.0 percent by weight. In another embodiment, the core comprises a tin alloy containing tin in an amount from 90 percent to 99 percent by weight. 
     In some embodiments, some or all of the protrusions have a circumferential width along the inside of the shank portion that is greater than a circumferential width of a gap between adjacent ones of the plurality of protrusions along the inside of the shank portion. 
     In some embodiments, the plurality of protrusions includes a first protrusion positioned opposite the central axis from a second protrusion. In other embodiments, the plurality of protrusions includes at least three protrusions evenly distributed about the central axis. In some embodiments, each of the plurality of protrusions extends into the core along a protrusion axis defining a locking angle with an adjacent inside surface of the shank portion forward of the plurality of protrusions, the locking angle from 45° to 120°. 
     In one such embodiment, the locking angle is from 85° to 95°. In another embodiment, the locking angle is greater than 90°. In yet another embodiment, the locking angle is from 60° to 120°. 
     In some embodiments, each of the protrusions extends into the core a distance from 0.015″ to 0.100″. 
     In some embodiments, the ogive portion has a tangent ogive shape. In other embodiments, the ogive portion has a secant ogive shape. 
     In some embodiments, the tip portion of the core protrudes from the open front end of the jacket and defines a rounded tip continuous with an outer surface of the jacket. For example, the projectile is configured as a soft-point projectile. 
     In some embodiments, the tip portion of the core defines a cavity recessed from the open front end of the jacket. For example, the projectile is configured as a hollow-point projectile. In other embodiments, the projectile includes a tip insert having a tip shank portion extending axially into the cavity through the open front end of the jacket, and having a tip portion seated against the open front end. For example, the tip insert comprises a polymer. 
     In some embodiments, the firearm projectile is an expanding projectile. Any of the embodiments of the projectile may include a cartridge casing with a mouth, where the projectile is retained in the mouth of the cartridge casing. 
     Another aspect of the present disclosure is directed to a method of manufacturing an expanding firearm projectile. In one embodiment, the method includes providing a cylindrical pre-form of metal and having a sidewall extending along a central axis from a closed rear end to an open front end, where the sidewall has a rear sidewall portion with a rear sidewall thickness, a forward sidewall portion with a forward sidewall thickness less than the rear sidewall thickness, and a shoulder between the rear sidewall portion and the forward sidewall portion; forming a plurality of core-locking protrusions in the cylindrical pre-form to provide a processed jacket, the plurality of core-locking protrusions circumferentially spaced and extending generally towards the open front end from a forward portion of the rear sidewall portion; providing a core of malleable material, the core having a first core portion with a first diameter, a neck portion with a neck diameter smaller than the first diameter, and a core shoulder between the first core portion and the neck portion; placing the core in the processed jacket with the neck portion extending towards the rear end through a space defined radially between the plurality of core-locking protrusions and with the core shoulder disposed in contact with ends of the plurality of core-locking protrusions; seating the core in the processed jacket to provide a cylindrical pre-form, thereby bending each of the plurality of core-locking protrusions radially inward and embedding the plurality of core-locking protrusions into the rearward core portion; and forming the cylindrical pre-form into a projectile with a jacket encasing the core except at an open front end, where the projectile has a shank portion with a cylindrical shape and an ogive portion with an ogival shape extending forward from the shank portion to a projectile tip. 
     In some embodiments, forming the plurality of core-locking protrusions is performed by axially impacting and penetrating the shoulder and a forward portion of the rear sidewall portion of the jacket pre-form. For example, the shoulder is axially impacted and penetrated with a cylindrical, multi-bladed dividing punch. 
     In some embodiments, forming the plurality of core-locking protrusions includes forming the plurality of core-locking protrusions extending forward along a protrusion axis defining an angle from 15° to 45° with respect to an adjacent inside surface of the forward sidewall portion. 
     In some embodiments, seating the core in the processed jacket includes axially compressing the core, thereby displacing air between the core and the processed jacket with the core. 
     In some embodiments, forming the cylindrical pre-form into the projectile is performed by forcing the cylindrical pre-form into an ogival-shaped die. 
     In some embodiments, seating the core in the processed jacket causes each of the plurality of core-locking protrusions to define a core-locking angle from 60° to 120° with respect to an adjacent inside surface of the forward sidewall portion. In some embodiments, seating the core in the processed jacket causes each of the plurality of core-locking protrusions to extend into the rearward core portion with the core-locking angle from 85° to 95°. In other embodiments, seating the core in the processed jacket causes each of the plurality of core-locking protrusions to extend into the rearward core portion with the core-locking angle greater than 90°. 
     In some embodiments, forming the plurality of core-locking protrusions includes defining at least some of the plurality of core-locking protrusions to span a protrusion sector about the central axis that is greater than a gap sector of a gap between adjacent core-locking protrusions. 
     In some embodiments, forming the plurality of core-locking protrusions includes defining a first core-locking protrusion positioned opposite the central axis from a second core-locking protrusion. 
     In some embodiments, forming the plurality of core-locking protrusions includes defining at least three core-locking protrusions evenly distributed about the central axis. 
     In some embodiments, forming the cylindrical pre-form includes forming the rear sidewall thickness to be from 2.0 to 2.75 times the forward sidewall thickness. 
     In some embodiments, seating the core in the processed jacket causes each of the plurality of core-locking members to extend into the core a distance from 0.015″ to 0.100″. 
     In some embodiments, the malleable material is selected from lead, a lead alloy, a lead-antimony alloy, tin, or a tin alloy. In some embodiments, the malleable material is a lead-antimony alloy containing antimony in an amount from 0.25 percent to 6.0 percent by weight. In another embodiment, the malleable material is a tin alloy containing tin in an amount from 90 percent to 99 percent by weight. 
     In another embodiment, forming the cylindrical pre-form into the projectile includes forming the ogive portion to have a tangent ogive shape or a secant ogive shape. 
     In another embodiment, forming part of the forward sidewall portion into an ogival shape causes the core to protrude from the open front end and define a rounded tip with exposed malleable material that is continuous with an outer surface of the ogive portion. 
     In another embodiment, the method includes defining a hollow-point cavity recessed from the open front end. 
     In another embodiment, the method includes defining a recess in the core adjacent the open front end, providing a tip insert having a tip stem portion and a tip portion, and installing the tip insert in the recess with the tip stem portion extending into the core through the open front end and the tip portion seated against the open front end of the jacket. In some embodiments, the projectile tip is selected to be made of a polymer. 
     Additional features of the present disclosure exist and will be described hereinafter and which will form the subject matter of the attached claims. These and various other advantages, features, and aspects of the embodiments will become apparent and more readily appreciated from the following detailed description of the embodiments taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional view of a profiled projectile oriented vertically, shown with a soft point tip, and including core-locking protrusions embedded in the core at a locking angle of 60 degrees, in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a longitudinal cross-sectional view of a profiled projectile oriented vertically, shown with a soft point tip, and including core-locking protrusions embedded in the core at a 90-degree locking angle, in accordance with an embodiment of the present disclosure. 
         FIG. 3  is a longitudinal cross-sectional view of a profiled projectile oriented vertically and shown with a soft point tip and core-locking protrusions embedded in the core at a 120-degree locking angle, in accordance with an embodiment of the present disclosure. 
         FIG. 4  is a longitudinal cross-sectional view of a profiled projectile oriented vertically, shown with a simple hollow point in its tip, and including core-locking projectiles embedded downward into the core at a 120-degree locking angle, in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a longitudinal cross-sectional view of a profiled projectile oriented vertically, shown with a polymer tip, and including core-locking protrusions embedded downward into the core at a 120-degree locking angle, in accordance with an embodiment of the present disclosure. 
         FIG. 6  is a flow chart illustrating example steps in a method of making an expanding projectile, in accordance with an embodiment of the present disclosure. 
         FIG. 7  is a longitudinal cross-sectional view of an empty cylindrical jacket pre-form oriented vertically and shown prior to the formation of multiple core-locking protrusions, in accordance with an embodiment of the present disclosure. 
         FIG. 8  is an isometric view of a multi-bladed dividing punch useful to form core-locking protrusions, in accordance with an embodiment of the present disclosure. 
         FIG. 9  is a side view of the bladed, working end of the multi-bladed dividing punch shown in  FIG. 8 . 
         FIG. 10A  is an end view of the bladed, working end of the multi-bladed dividing punch shown in  FIG. 9 . 
         FIG. 10B  is a larger, more detailed end view of the working end of the multi-bladed dividing punch shown in  FIG. 10A . 
         FIG. 11  is a section taken along line A-A of  FIG. 10A  showing a longitudinal cross-sectional view of the bladed, working end of the multi-bladed dividing punch. 
         FIG. 12  is a section taken along line B-B of  FIG. 10A  showing a longitudinal cross-sectional view of the bladed, working end of the multi-bladed dividing punch. 
         FIG. 13A  is an end view of an empty, cylindrical processed jacket showing four core-locking protrusions that have been formed by the multi-bladed dividing punch shown in  FIGS. 8-12 , in accordance with an embodiment of the present disclosure. 
         FIG. 13B  is a larger, more detailed end view of the processed jacket shown in  FIG. 13A . 
         FIG. 13C  is a longitudinal cross-sectional view of the processed jacket taken along line C-C of  FIG. 13A , showing the geometry of the spaced core-locking protrusions. 
         FIG. 13D  is a longitudinal cross-sectional view of the processed jacket taken along line D-D of  FIG. 13A , showing the geometry of the spaced core-locking protrusions. 
         FIG. 14  is a larger, more detailed longitudinal cross-sectional view of the processed jacket shown in  FIG. 13D . 
         FIG. 15A  is a side view of a malleable core having a long leading end prior to insertion into the empty processed jacket shown in  FIG. 14 , in accordance with an embodiment of the present disclosure. 
         FIG. 15B  is a longitudinal cross-sectional view of the core of  FIG. 15A . 
         FIG. 16  is a longitudinal cross-sectional view of both the processed jacket and a core with a long leading end after the core has been dropped into a processed jacket, in accordance with an embodiment of the present disclosure. 
         FIG. 17  is a longitudinal cross-sectional view of the processed jacket and the core with a long leading end of  FIG. 16  after the core has been partially seated in the jacket, in accordance with an embodiment of the present disclosure. 
         FIG. 18  is a longitudinal cross-sectional view of the processed jacket and the core with a long leading end of  FIG. 16  after the core has been fully seated in the jacket, thus forming a cylindrical pre-form, in accordance with an embodiment of the present disclosure. 
         FIG. 19  is a longitudinal cross-sectional view of both the processed cylindrical jacket and a core with a short leading end after the core has been dropped into a processed jacket, in accordance with an embodiment of the present disclosure. 
         FIG. 20  is a longitudinal cross-sectional view of the processed cylindrical jacket and the core with a short leading end shown in  FIG. 19  after the core has been partially seated in the jacket, in accordance with an embodiment of the present disclosure. 
         FIG. 21  is a longitudinal cross-sectional view of the processed cylindrical jacket and the core with a short leading end shown in  FIG. 19  after the core has been fully seated in the jacket, thus forming a cylindrical pre-form, in accordance with an embodiment of the present disclosure. 
         FIG. 22  is a longitudinal cross-sectional view of a profiled, fully-formed projectile made in accordance with a method of the present disclosure, where the core-locking protrusions in the cylindrical pre-form of  FIG. 17  were pre-set at a 60-degree locking angle during the core-seating process with a core having a long leading end, and after the cylindrical pre-form was forced into an ogival die. 
         FIG. 23  is a longitudinal cross-sectional view of a profiled, fully-formed rifle projectile made in accordance with a method of the present disclosure, where the core-locking protrusions in the cylindrical pre-form of  FIG. 20  were pre-set at a 120-degree locking angle during the core-seating process with a core having a short leading end, and after the pre-form was forced into an ogival die. 
         FIG. 24  is an elevational view of a firearm cartridge with a projectile retained in the mouth of the cartridge casing, in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is generally directed to embodiments of an expanding projectile useful in hunting, law enforcement, and personal protection, and a method of making the projectile. In accordance with some embodiments of the present disclosure, a jacketed projectile prevents or greatly reduces jacket-core separation by providing a jacket with a plurality of core-locking protrusions extending from the inside jacket wall into a projectile core. The core-locking protrusions are embedded into the projectile core at a locking angle defined relative to the adjacent jacket wall. For example, the locking angle is from 30° to 120°, such as 30°, 60°, 90°, or 120°. 
     General Overview 
     For a projectile to achieve optimum terminal performance, it is desirable that its jacket and core penetrate a target as a single unit and remain connected throughout the course of travel, regardless of the resistance offered by the target material. 
     Various attempts have been made over the years to form projectiles where the projectile&#39;s jacket and core remain coupled together on impact. One of the earliest and simplest attempts utilized a knurling process to create a cannelure in a jacketed projectile. A cannelure typically includes a narrow, 360-degree circumferential depression in the shank portion of the projectile jacket. The cannelure originally was conceived to serve as a crimping feature, where the mouth or rim of the cartridge case is mechanically forced radially inward into the cannelure to secure the projectile in the cartridge case. Various manufacturers have since attempted to use the cannelure as a crimping groove and a core-retaining feature, or simply a core-retaining feature. 
     The knurling process typically utilizes a multi-tooth knurling wheel that cuts into the jacket and forces the jacket material radially inward into the core. The result is a shallow annular rim that extends a short distance into the projectile core. Due to this process, the jacket wall can often be weakened circumferentially in both the fore and aft areas of the cannelure. This weakness deficit is evidenced in the U.S. Military&#39;s M193 rifle projectile, where the projectile breaks into two pieces at the cannelure during target impact as the projectile loses stability and begins to tumble or gyrate around its own axis. 
     The cannelure approach has also proven to be ineffective in keeping the core and jacket together upon impact with a target, such as a game animal. Upon impact, the core tends to immediately extrude beyond the confines of the shallow rim-like protrusion extending into the cannelure and subsequently slides completely out of the jacket. Depending on jacket wall thickness, core hardness, impact energy, and especially on the inertial forces that develop on impact, axial core movement can actually smooth the internal geometry of the cannelure to a degree that allows the core to slide forward. In addition, when impacting hard barriers, the jacket can crack and/or be severed circumferentially along the inherently weakened, fore and aft boundaries of the cannelure. Such a failure can result in jacket-core separation and a concurrent loss in projectile mass and momentum, thereby reducing target penetration. Even the use of multiple cannelures have proven ineffective in retaining the core with the jacket due to the shallow depth of each cannelure and the inadequate amount of area the cannelures collectively occupy. 
     U.S. Pat. No. 4,336,756 (Schreiber) describes a bullet intended for hunting. The Schreiber bullet has a jacket utilizing a cannelure plus an annular ledge on the inside surface of the jacket with an inwardly-extending ring of jacket material terminating in a knife-like edge to engage the core. The annular ledge is spaced from the base portion of the jacket. The ledge is formed with blunt upper and lower punches moving in opposite directions to cause the metal at a ledge in the jacket to flow inwardly and form an annular ridge. 
     One shortcoming associated with the Schreiber approach is the limited radial width of the annular ring of jacket material. Accordingly, the ring does not extend sufficiently into the projectile core and therefore cannot provide adequate core-holding ability. In order to retain the core together with the jacket on impact with a target, the circular ring depends on the additional assistance of a cannelure. The combination of the ring and the cannelure is required to ensure the core and the jacket remain locked during expansion. Attempts to increase the radial width of the ring cause the heel of the jacket to become sharpened as the heel collapses axially and flattens. This outcome is undesirable because it degrades projectile accuracy. Also, increasing the axially-directed force to gather more jacket material and increase the ring&#39;s radial distance results in cracks along the ring&#39;s circumference. 
     U.S. Pat. No. 4,856,160 (Habbe, et al.) describes a bullet with a tubular jacket having a reverse taper. The jacket wall is thicker at the intermediate portion than either the heel or mouth portions to define a reverse taper along the intermediate and heel portions. The reverse taper bulges inwardly at the intermediate portion compared to the heel portion interior. The reverse taper provides an inside diameter at the jacket intermediate portion that is less than at the jacket heel portion and in such manner produces a constriction that interlocks the lead core and jacket together. 
     The downside to the Habbe, et al. approach is that the reverse taper portion of the jacket has a shallow angle which does not grip the core in an aggressive manner and therefore allows the core to slip on impact. Like the Schreiber bullet, the failure to securely grip the core is why a roll crimp (or “bullet knurl”) is also required to retain the core within the jacket upon impact with a target. 
     U.S. Pat. No. 9,188,414 (Burczynski) describes a reduced-friction expanding bullet with an improved core retention feature. The cylindrical jacket is forced into a die to create at the same time a wide-area circumferential indentation and an ogival bullet nose. The circumferential indentation is formed as a wide-area radiused depression that contacts the core and serves as a living hinge to facilitate flexing and bending of portions of the ogive as the ogive impacts a target and expands. 
     A challenge of the Burczynski approach is that thick-wall jacketed pre-forms can be difficult to collapse during manufacture, therefore limiting the materials used to produce the jacket and increasing the cost of manufacture. 
     Other attempts at retaining the core together with the jacket after impact with a target have been used in the past. Such attempts include (1) providing a partition within the jacket that separates a rear core from a front core, (2) electroplating a copper skin around the core prior to final forming of the projectile, and (3) heat-bonding the core to the interior of the jacket wall after the projectile is final-formed. These additional methods can have one or more shortcomings that include jacket-core eccentricity that results in reduced accuracy in flight due to projectile imbalance. Another shortcoming is limited or insufficient core-holding ability. Further shortcomings are slower manufacturing rates, high or increased manufacturing costs, and/or lower reliability. 
     In light of the aforementioned shortcomings, a need exists for a new and improved expanding projectile with superior core-retaining ability without sacrificing projectile performance. The various embodiments of the present disclosure fulfill this need. 
     Example Projectile Configurations 
       FIG. 1  illustrates a longitudinal cross-sectional view of a projectile  100  shown in an upright orientation, in accordance with an embodiment of the present disclosure. Projectile  100  is fully formed and includes a hollow jacket  82  surrounding a malleable core  92  disposed in the jacket  82 . In some embodiments, the core  92  is made of lead or a lead alloy. Other materials with a malleability greater than that of pure copper are acceptable for core  92 . As shown in  FIG. 1 , projectile  100  is configured as a jacketed soft point (JSP) projectile suitable for rifle cartridges, where the projectile tip  20  is an exposed extension of the core  92 . Projectile  100  of  FIG. 1  includes features common to other embodiments discussed below and shown, for example, in  FIGS. 2-5  and  FIGS. 22 and 23 . 
     Projectile  100  has a generally cylindrical shape that is rotationally symmetrical about a central axis  15 . The projectile  100  extends from a rear end  78  to a forward terminus  34  of the projectile tip  20 , which can be an extension of the core  92  as shown in  FIG. 1 . The projectile  100  has an outside surface  82   a  defined along the jacket  82  and the projectile tip  20 . Projectile tip  20  may be defined by the core  92  extending through the open front end  99  as shown for example in  FIG. 1 , by the front end  99  of the jacket  82  (e.g., a hollow-point projectile tip  20 ), or by a tip insert  30 , depending on whether the projectile  100  has a soft point configuration, a hollow point configuration, a polymer tip configuration, or some other configuration. The projectile  100  has a cylindrical shank  86  that includes a closed rear end  78 , a rear sidewall  93 , and part of a forward sidewall  94 . Shank  86  continues forward to an ogive portion  88  that includes part of forward sidewall extending to an open front end  99 . The ogive portion  88  has a gentle curve toward the meplat  22  of the projectile tip  20 . In some embodiments, the projectile  100  has a flat rear end  78  that transitions to the rear sidewall  93  with a rounded heel  68 . For improved projectile accuracy, the rounded heel  68  can have a relatively large radial width approximate to that of jacket  82  overall. 
     The jacket  82  is hollow with an outside surface  82   a  and an inside surface  82   b . Jacket  82  has a base portion  80 , a rear sidewall  93 , and a forward sidewall  94  that extends from rear sidewall  93  to open front end  99 . The rear sidewall  93  connects to and extends between the base portion  80  and the forward sidewall  94 . The forward sidewall  94  extends forward from the rear sidewall  93  and along the ogive portion  88  to an open front end  99  with rim a  96 . In some embodiments, jacket  82  is formed of copper, a copper alloy, cupronickel, steel, brass, gilding metal, or other metal. In general, jacket  82  is made of a material (e.g., copper alloy or other metal) that is harder and less malleable than core  92  (e.g., a lead alloy). Other materials with comparable malleability are acceptable depending on the intended use of projectile  100 . 
     In some embodiments, jacket  82  has two distinct wall thicknesses: a rear sidewall thickness T 2  is thicker than a forward sidewall thickness T 1 . The difference in wall thickness ultimately depends on the projectile type and its intended use. In some embodiments, for example, jacket  82  has a wall thickness ratio of 2:1, where the rear sidewall thickness T 2  is about twice as thick as the forward sidewall thickness T 1 . In other embodiments, jacket  82  has a different value of the wall thickness ratio, such as embodiments in which projectile  100  is heavy and/or a high velocity projectile that develops high inertial forces on impact. In such embodiments, the rear sidewall thickness T 2  can be as much as 2.75 times thicker than the forward sidewall thickness T 1 . The wall thickness may transition abruptly or gradually from rear sidewall thickness T 2  to forward sidewall thickness T 1 . 
     Jacket  82  defines a plurality of circumferentially-spaced core-locking protrusions  65  that extend radially inward from inside surface  82   b  of rear sidewall  93  adjacent forward sidewall  94 . In some embodiments, core-locking protrusions  65  (or simply “protrusions”) are evenly spaced in a circular pattern along the inside surface  82   b  of the jacket  82 . For example, portions of the thicker rear wall  93  adjacent the forward sidewall  94  are formed into a plurality of core-locking protrusions  65  arranged in a circular pattern and extending longitudinally and radially inward towards the central axis  15  of the projectile  100 . The jacket  82  can include two or more core-locking protrusions  65 . One example embodiment has four core-locking protrusions  65 . Core-locking protrusions can be evenly distributed circumferentially about central axis  15 , but this is not required so long as projectile  100  is balanced, as will be appreciated. The thickness of each core-locking protrusion  65  depends on the rear sidewall thickness T 2 . As the rear sidewall thickness T 2  increases for a given forward sidewall thickness T 1 , core-locking protrusions  65  can be thicker, stiffer, and more robust. In example embodiments, one or more of the core-locking protrusion  65  has an elongated shape similar to a spike or tooth, where the cross-sectional shape of the core-locking protrusion  65  is square or rectangular. In other embodiments, one or more of the core-locking protrusions  65  have a wedge shape extending from about 10-90° along the circumference of the sidewall, including 20°, 30°, 40°, 50°, 60°, 70°, and 80°. The core-locking protrusions  65  can be radially embedded into a rear portion of the core  92  to a depth between about 0.015″ and 0.100″, depending on projectile caliber, weight and type. 
     When core-locking protrusions  65  are initially formed from rear sidewall  93 , they generally extend in a forward direction and slightly away from inside surface  82   b  of forward sidewall  94 . Core-locking protrusions  65  shown in  FIG. 1  have been bent rearwardly from their initial position to a final locking angle α as a result of a process used to seat the core  92  in a pre-form version of the jacket  82 . Accordingly, each core-locking protrusion  65  shown in  FIG. 1  defines a locking angle α of about 60 degrees with respect to forward sidewall  94 . In the finished projectile  100  as shown, for example, in  FIG. 1 , core-locking protrusions  65  are embedded in core  92  with each core-locking protrusion  65  surrounded by and contacting the core  92 . In some embodiments, locking angle α is in a range from 60° to 120° as defined between a protrusion axis  60  and forward sidewall  94 . Any value of locking angle α within that range is acceptable. In other embodiments, locking angle α can be less than 60° or greater than 120°. Specific locking angles α may serve specific purposes with respect to various projectiles  100 . Regardless of the locking angle α, a locking chamber  67  is defined between the base  80 , the rear jacket wall  93 , and the core-locking protrusions  65 . 
     While a tangent ogive is shown in  FIG. 1  (as well as the projectile examples shown in  FIGS. 2-5  and  FIGS. 22 and 23 ), projectiles  100  made in accordance with some embodiments of the present disclosure can utilize either a tangent ogive or a secant ogive. A secant ogive has the potential to increase the ballistic coefficient of the projectile due to a more pointed and streamlined profile. For example, the secant ogive shape is advantageous for extremely long-range shooting since the projectile retains a higher velocity at long distances. It is also contemplated that while a flat base  80  is shown in  FIGS. 1-5, 22 and 23 , base  80  can have a “boat tail” shape (e.g., a frustocone or taper) for an improved ballistic coefficient. 
       FIG. 2  illustrates a longitudinal cross-sectional view of a fully formed projectile  100  made in accordance with another embodiment of the present disclosure. Projectile  100  is particularly useful in rifle ammunition and is configured as a soft-point projectile with a projectile tip  20  of exposed core  92  material. Core-locking protrusions  65  have been forced during the seating process to provide locking angle α from about 85-95 degrees with respect to inside surface  82   b  of forward sidewall  94 . In other embodiments, locking angle α is from 88-92 degrees, such as 90 degrees. The locking angle α of about 90 degrees (as well as other locking angles) is substantially maintained while forming the completed projectile  100  due to equilibrium of forces during the core-seating process. A 90-degree locking angle α may be desirable when the projectile  100  is launched from a very high-velocity cartridge as a more pronounced locking angle α provides enhanced core-gripping ability upon impact with a target. 
       FIG. 3  illustrates a longitudinal cross-sectional view of a fully-formed projectile  100  made in accordance with another embodiment of the present disclosure. Projectile  100  is well-suited for use in rifle cartridges and is configured as a soft-point projectile with projectile tip  20  of exposed core  92  material. Core-locking protrusions  65  have been forced during the core-seating process to assume locking angle α of about 120 degrees with respect to inside surface  82   b  of forward sidewall  94 . A locking angle α greater than 90 degrees, such as 120 degrees, may be desirable when the projectile  100  is launched from a very high-velocity cartridge and also has a substantial core mass, thereby generating a very high inertial force during impact with a target. Core-locking protrusions  65  set at locking angle α of about 120 degrees can provide a very high degree of core-gripping ability to arrest forward movement of core  92  within jacket  82  upon impact with a target. 
       FIG. 4  illustrates a longitudinal cross-sectional view of a fully formed projectile  100  made in accordance with another embodiment of the present disclosure. Similar to embodiments discussed above, projectile  100  is well-suited for use in rifle cartridges. Projectile  100  is configured with a hollow-point cavity  97  defined within open front end  99 . A generally flat projectile tip  20  across rim  96  of open front end  99  provides a wider meplat  22  than soft-point configurations, such as depicted in  FIGS. 1-3 . While a simple conical shape is shown, cavity  97  may assume any desired shape, including frustoconical, cylindrical, spherical, ovoid, and the like. The forward terminus  34  of projectile  100  can be the rim  96  of jacket  82  without exposed core  92  material forward of the rim  96 . Core-locking protrusions  65  shown in  FIG. 4  are set at locking angle α of about 120 degrees as a result of the core-seating process, but any locking angle α from 60 to 120 degrees is acceptable. A locking angle α of about 120 degrees provides a further improved core-gripping ability that is often desirable in a hollow point projectile  100 , especially if both ogive portion  88  and forward sidewall  94  of shank  86  greatly expand radially on impact. The hollow-point projectile tip  20  with cavity  97  is shown here to illustrate an example of the many projectile tip  20  options contemplated for projectiles  100  of the present disclosure. 
       FIG. 5  illustrates a longitudinal cross-sectional view of a fully formed projectile  100  made in accordance with another embodiment of the present disclosure. Similar to embodiments discussed above, projectile  100  shown in  FIG. 5  is well-suited for use in rifle cartridges. Projectile  100  shown in  FIG. 5  is configured with a tip insert  30  that defines projectile tip  20  and extends through open front end  99  into core  92 . Tip insert  30  is made of a polymer in some embodiments, but can be made of other materials including ceramic, metal, and other materials. Tip insert  30  has a tip shoulder  48  that is received against rim  96  of jacket  82  with an exposed tip portion  62  extending forward of open front end  99  of ogive portion  88  to a pointed or rounded forward terminus  34 . In some embodiments, tip insert  30  can be pointed at its forward terminus  34  to provide a reduced meplat  22  for an improved ballistic coefficient for projectile  100 . A tip shank portion  50  extends rearwardly from exposed tip portion  62  and includes a first shank portion  51  of larger diameter S 1  and a second shank portion  52  of smaller diameter S 2  rearward of the first shank portion  51 . Core  92  defines a generally cylindrical cavity  97  with a first cavity portion of larger diameter S 1  sized for and corresponding to first shank portion  51  of larger diameter S 1 , and a second cavity portion of smaller diameter S 2  sized for and corresponding to a second shank portion  52  of smaller diameter S 2 . 
     First shank portion  51  of larger diameter S 1  is tightly gripped by rim  96  adjacent tip shoulder  48  to retain tip insert  30  with core  92 . In some embodiments, projectile  100  defines a centralized air gap  76  in cavity  97 , where air gap  76  is positioned axially between a rear end  54  of tip shank portion  50  and bottom  91  of cavity  97 . Air gap  76  can be of any size and shape. A purpose of air gap  76  is to facilitate projectile expansion as tip insert  30  is driven rearward into core  92  upon impacting a target. As discussed above for hollow-point projectile  100  of  FIG. 4 , a locking angle α of about 120 degrees may be used when projectile  100  includes tip insert  30 . Tip insert  30  is shown here to illustrate another example of the many projectile tip  20  options contemplated for projectiles  100  of the present disclosure. 
     It is contemplated that any configuration of projectile tip  20  can be used in each of the embodiments presented in  FIGS. 1-5  and  FIGS. 22 and 23 , regardless of the ultimate locking angle α of the core-locking protrusions  65 . It is also contemplated that any type or number of nose-weakening features (e.g., skives, scores, slits, etc.) can be used in any embodiment of the present disclosure to facilitate expansion of projectile  100  on impact. 
     It is further contemplated that any of the features discussed above may be used in projectiles  100  configured for rifle ammunition or pistol ammunition. A projectile  100  for pistol ammunition with ogive portion  88  can be configured, for example, with a tangent ogive shape, a truncated cone nose profile, or other shape. Regardless of its ogive curvature, nose angle, or profile, a much wider meplat  22  than that shown for the projectile in  FIG. 4  would normally be used for pistol ammunition. The shape of the projectile tip  20  in a projectile  100  used with pistol ammunition may generally be flat, but its meplat  22  can be much wider than the flat projectile tip  20  and meplat  22  shown in projectile  100  of  FIG. 4 . A flat projectile tip  20  may also incorporate a hollow-point cavity  97  of any desired shape. The forward terminus  34  of the projectile tip  20  in a pistol projectile may comprise jacket  82  material or, if desired, can be exposed lead or any other malleable core  92  material. 
     Referring now to  FIG. 6 , a flowchart illustrates example steps in a method  400  of making an expanding projectile  100  in accordance with the present disclosure. Method  400  is further discussed below with reference to  FIGS. 7-21 , which illustrate embodiments of projectile  100  in various stages of production as well as a dividing punch used in one method of forming core-locking protrusions  65 , in accordance with some embodiments. 
     In one embodiment, method  400  includes providing  405  a jacket pre-form  150  having a rear sidewall  93  and a forward sidewall  94 , where the rear sidewall thickness T 2  is greater than the forward sidewall thickness T 1 , and where the jacket pre-form  150  defines a shoulder  61  between the forward sidewall  94  and the rear sidewall  93 . In some embodiments, providing  405  the jacket pre-form  150  optionally includes providing  401  a cylindrical cup with a closed end and an open end and then elongating  402  the cylindrical cup into the jacket pre-form. As a further option, the pre-form front end  102  of the jacket pre-form  150  can be trimmed  403  as needed to define rim  96  with the desired profile. Next, a plurality of core-locking protrusions  65  are formed  410  from the inside of rear sidewall portion  93  of jacket pre-form  405 . 
     In one embodiment, core  92  is formed or provided  415  with a first core portion  33 , a neck portion  36 , and a core shoulder  31  between the first core portion  33  and the neck portion  36 . Core  92  is dropped or otherwise placed  420  in jacket pre-form  150  with core shoulder  31  supported by core-locking protrusions  65 . Core  92  is seated  425  in jacket pre-form  150 , resulting in a cylindrical pre-form  220  with the core-locking protrusions  65  embedded in the core  92 . In some embodiments, the step of seating  425  the core  92  involves two actions performed, for example, using a flat-ended seating punch. First, core  92  is compressed axially to bend core-locking protrusions  65  to locking angle α and to partially embed core locking protrusions  65  into core  92 . Next, core  92  is further axially compressed and caused to radially expand to fill the locking chamber  67  and to fully embed core-locking protrusions  65  in core  92 . This second portion of seating  425  core  92  displaces gaps between the jacket pre-form  150  and core  92  with core  92  material. 
     The cylindrical pre-form  220  is subsequently formed  430  into projectile  100  having jacket  82  encasing the core  92  except at the open front end  99  and with core-locking protrusions  65  embedded in core  92 . Examples and further details of steps in method  400  are discussed below. 
       FIG. 7  illustrates a longitudinal cross-sectional view of an empty cylindrical jacket pre-form  150  prior to the forming  405  core-locking protrusions  65 . The jacket pre-form  150  is formed, for example, by providing  401  a shorter, thick-walled copper or copper-alloy cup (not shown). The cup is subjected to a series of draw steps using cylindrical dies and two-diameter punches of various sizes. In doing so, the cup is elongated  402  into jacket pre-form  150  as shown in  FIG. 7  with a smaller forward sidewall thickness T 1 , a larger rear sidewall thickness T 2 , and a transition portion  77  between forward sidewall  94  and rear sidewall  93 . 
     In some embodiments, jacket pre-form  150  has an open mouth area  98  with a pre-form front end  102  of irregular shape. Optionally, pre-form front end  102  can be trimmed  403  as needed, such as by pinch-trimming, to define a rim  96  with an inside radius  95 . After trimming  403  the pre-form front end  102 , the circular rim  96  at the pre-form front end  102  extends substantially perpendicular to central axis  15 . The resulting jacket pre-form  150  is a cylindrical tube that is symmetrical in rotation about central axis  15  with a closed rear end  78  and an open pre-form front end  102  with rim  96  that extends substantially perpendicularly to central axis  15 . The cylindrical jacket pre-form  150  comprises three portions that include (i) a cylindrical rear portion  71  with a closed rear end  78  and a rear sidewall  93  with rear sidewall thickness T 2 , (ii) a transition portion  77  comprising a convexly-rounded shoulder  61  extending from inside surface  82   b  of rear sidewall  93  to a concavely-rounded region  63  extending from shoulder  61  to inside surface  82   b  of forward sidewall  94 , and (iii) a forward portion  101  comprising a thinner forward wall  94  with forward sidewall thickness T 1  that is less than rear sidewall thickness T 2 . The inside surface  82   b  of forward sidewall  94  and/or rear sidewall  93  can be parallel to central axis  15 , or if desired, can have a slight amount of draft or taper. 
       FIG. 8  illustrates an isometric view of a multi-bladed dividing punch  130  used in one embodiment of method  400  to form  410  core-locking protrusions  65 . The dividing punch  130  can be slidably received within a cylindrical die (not shown). The dividing punch  130  has a punch alignment end  11  with a first length L 1  and a working end  12  with a second length L 2 . Alignment end  11  has a first diameter D 1  and working end  12  has a second diameter D 2 . The overall length of the dividing punch  130  equals the sum of first length L 1  and second length L 2 , and can be any length desired to allow compatibility and functionality when installed in high-speed production machinery. The dividing punch  130  can utilize threads or any other means necessary to secure it within the high-speed production machinery. In some embodiments, first diameter D 1  of alignment end  11  is about 0.0005″ to 0.001″ inch smaller than the inside diameter of the cylindrical die within which it operates. In some embodiments, working end  12  of dividing punch  130  has a diameter D 2  that is between about 0.0005″ and 0.0015″ smaller than the inside diameter of the forward sidewall  94  of jacket pre-form  150  (shown in  FIG. 7 ). 
     The working end  12  of the dividing punch  130  has a plurality of blades  14  separated from one another by an equal number of U-shaped slots or windows  16 . Windows  16  can be cut out of working end  12  using, for example, a milling process or an Electric Discharge Machine (EDM) process. In one embodiment, the dividing punch  130  has four blades  14  for making four core-locking protrusions  65  in jacket  82 . The working end  12  of the dividing punch  130  has a sharp cutting edge  18 . For example, the cutting edge  18  has an edge width from about 0.005″ to 0.015″, rendering cutting edge  18  sufficiently sharp to penetrate the shoulder  61  of the cylindrical jacket pre-form  150 . The second length L 2  of the working end  12  of the dividing punch  130  includes additional axial length  13  compared to jacket  82  in order to accommodate the thickness of a stripper disk or stripper plate (not shown) used to strip the processed jacket  160  (shown, e.g., in  FIGS. 13A-13 -D, and  FIG. 14 ) off the working end  12  of the dividing punch  130  after the core-locking protrusions  65  have been formed  410 . 
       FIGS. 9, 10A, 10B, 11, and 12  illustrate various views of a portion of the working end  12  of the dividing punch  130  shown in  FIG. 8 .  FIG. 9  is a side view of a forward portion of the working end  12  of the dividing punch  130 .  FIG. 10A  is an end view of the working end  12  of the dividing punch  130  showing the sectional directionality associated with  FIGS. 11 and 12 .  FIG. 10B  is an enlarged end view of the dividing punch  130  of  FIG. 10A  showing details of the U-shaped windows  16  between adjacent blades  14 . In some embodiments, working end  12  includes a fillet  17  (i.e., a small radius) adjacent a central base  19  between blades  14  for added strength. 
       FIG. 11  is a longitudinal cross-sectional view of working end  12  taken along line A-A of  FIG. 10A  and shows a forward portion of the bladed, working end  12  of the dividing punch  130 .  FIG. 12  is a longitudinal cross-section taken along line B-B of  FIG. 10A  and shows a portion of the bladed, working end  12  of the dividing punch  130 . The blades  14  include cutting edge  18  and are spaced circumferentially by windows  16 . It has been discovered that the optimum blade angle β in some embodiments of each dividing punch  130  blade  14  is 30 degrees. In other embodiments, blade angle β can have other values, such as being increased to 45 degrees. The sharp cutting edge  18  of the blades  14  allows the dividing punch  130  to easily penetrate the shoulder  61  of the empty cylindrical jacket pre-form  150 . In some embodiments, each blade  14  has an axial height  21  from about 0.075″ to about 0.250″, depending on projectile diameter and the ultimate application or use of the projectile  100 . 
       FIGS. 13A, 13B, 13C, and 13D  illustrate various views of an empty, processed jacket  160  after the shoulder  61  area of the jacket pre-form  150  has been penetrated by the blades  14  on the working end  12  of the dividing punch  130  (shown in  FIG. 8 ).  FIG. 13A  is an end view of a processed jacket  160  showing the sectional directionality associated with  FIGS. 13C and 13D .  FIG. 13B  is an enlarged end view of the processed jacket  160  shown in  FIG. 13A  and shows the result produced by the axially-directed penetration of four spaced blades  14  present in the working end  12  of an embodiment of the dividing punch  130 . As the dividing punch  130  begins its axial travel into the jacket pre-form  150 , the sharp cutting edge  18  on each blade  14  of the dividing punch  130  initially makes contact with the concavely-rounded region  63  of transition portion  77  (shown in  FIG. 7 ). As the dividing punch  130  continues into the jacket pre-form  150 , the blades  14  penetrate the shoulder  61  and a forward portion of the thicker rear sidewall  93  of the jacket  82 . This action ultimately forms core-locking protrusions  65  that each extend longitudinally and radially inward towards the axis  15  of the jacket  82  at blade angle β. In some embodiments, core-locking protrusions  65  are substantially symmetrical. After being formed, the core-locking protrusions  65  in the processed jacket  160  extend along protrusion axis  60  at blade angle β relative to the inside surface  82   b  of forward sidewall  94 , consistent with the blade angle β of the blades  14  of the dividing punch  130  (shown in  FIG. 11 ). In some embodiments, the blade angle β and the resulting angle of the core-locking protrusions  65  as initially formed can both be as great as 45 degrees. In other embodiments, the blade angle β and resulting angle of the core-locking protrusions is about 30 degrees. In yet other embodiments, the blade angle β and resulting angle of the core-locking protrusions is less than 30 degrees. Increasing the blade angle β from 30 to 45 degrees increases the strength of dividing punch  130 . 
     As shown in the end view of  FIG. 13B , one embodiment of processed jacket  160  has four core-locking protrusions  65  separated circumferentially by spaces  66 , where core-locking protrusions  65  and spaces  66  are evenly distributed and arranged symmetrically about central axis  15 . Each space  66  corresponds to a portion of rear sidewall  93  that is undisturbed by dividing punch  130  and retains a full rear sidewall thickness T 2 . That is, each space  66  aligns with the un-penetrated shoulder  61  of the jacket pre-form  150 . These solid, un-cut (un-penetrated) areas of shoulder  61  provide strength in the rear sidewall  93  adjacent the core-locking members  65  and prevent the jacket  82  from shearing, bending, collapsing or otherwise deforming upon impact with a hard target, such as bone, metal, or windshield glass. 
     Core-locking protrusions  65  can have a length as needed to engage core  92 . An increased length of core-locking protrusions  65  is accomplished by forcing the blades  14  of the dividing punch  130  to penetrate deeper into the rear sidewall  93  of the jacket  82 . However, a practical limit exists to the amount of axial height that can be achieved in the core-locking protrusions  65 . In some embodiments, a circumferential width “W” ( FIG. 13B ) of the spaces  66  separating the core-locking protrusions  65  from one another can be sized so that the corners  64  of neighboring core-locking protrusions  65  do not make contact with one another when the core  92  is seated within the jacket  82  and causes the core-locking protrusions  65  to extend radially inward towards the central axis  15 . A crowded arrangement of core-locking protrusions  65  could result in partial deformation of the core-locking protrusions  65  as they bend inwardly and approach a 90-degree locking angle α during the subsequent step of seating  425  the core  92 . With respect to the advantage gained, core-locking protrusions  65  of greater length ultimately provide even greater core-gripping ability since longer core-locking protrusions  65  can be forced further (e.g., radially) into the core  92  material during the step of seating  425  the core  92 . The steps of seating  425  the core  92  are discussed below with reference to  FIGS. 16-18  and  FIGS. 19-21 . In some embodiments, a circumferential width of core-locking protrusions  65  along the sidewall is greater than the circumferential width W of spaces  66 . In other embodiments, the circumferential width of core-locking protrusions  65  along the sidewall is less than the circumferential width W of spaces  66   
       FIG. 14  is a larger, more detailed view of the processed jacket  160  shown in  FIG. 13D . Processed jacket  160  has three basic portions along its length between the rear end  78  of the base portion  80  and the front end or rim  96 . Starting at the front or rim  96  and continuing rearward, processed jacket  160  has a relatively long forward sidewall  94  with forward sidewall thickness T 1 . A middle portion  83  represents the final axial height of the core-locking protrusions  65  after they have been fully formed and forced radially inward to about a 30-degree angle by the blades  14  of the dividing punch  130 . Rearward of the middle portion  83  is the rear sidewall  93  with a thicker rear sidewall thickness T 2  and closed base  80 . The inside surface  82   b  of rear sidewall  93  and forward sidewall  94  can be parallel to the central axis  15  or can have a slight amount of draft or taper. Locking chamber  67  is defined between the rear sidewall  93 , base  80 , and the interrupted area rearward of the core-locking protrusions  65 . Part of the core  92  is locked within the locking chamber  67  after the core  92  is seated  425  and the projectile  100  is formed  430 . 
       FIGS. 15A and 15B  show an example of core  92  having one of several core shapes that are compatible with a projectile  100  in accordance with some embodiments of the present disclosure. In some embodiments as noted above, core  92  material can be lead or a lead-based alloy containing antimony. The core  92  can be pure lead or may comprise a lead alloy containing as much as 6% antimony. Other acceptable core  92  materials include tin, tin alloy, bismuth, bismuth alloy, and other malleable or frangible materials. In some embodiments, core  92  is made of a metal or metal alloy that is softer and more malleable than pure copper. As such, core  92  can readily flow around core-locking protrusions  65  during the manufacturing process. 
       FIG. 15A  shows an elevational view of core  92  with an example of an acceptable shape to make projectiles  100  in accordance with embodiments of the present disclosure. Core  92  has a first core portion  33  with a generally cylindrical shape and a first core diameter D 3 . First core portion  33  extends from a forward end  105  to a core transition portion  35 . Core transition portion  35  is between first core portion  33  and a second core portion or neck portion  36  and defines a core shoulder  31  with a core shoulder angle γ. Neck portion  36  extends rearward from transition portion  35  to core rear end  79  with a generally cylindrical shape and a second core diameter D 4 , where second core diameter D 4  is smaller than first core diameter D 3 . In some embodiments, core shoulder angle γ is from 30° to 60° relative to central axis  15 , such as 45°. In some embodiments, core shoulder angle γ is some other value, such as 90° to provide an abrupt transition from first core portion  33  to neck portion  36 . A core shoulder angle γ from 30° to 60° facilitates alignment of the core  92  within the jacket  82  during high-speed production. An outside surface  33   a  of first core portion  33  and an outside surface  36   a  of neck portion  36  can be parallel to the central axis  15  or, if desired, can have a slight amount of draft or taper to facilitate expulsion of the core  92  from a forming die (not shown) where the core  92  is initially formed and bled to its final weight. 
     The length  38  of the neck portion  36  is important for determining the locking angle α of the core-locking protrusions  65 . A neck portion  36  of greater length  38  (as shown in  FIGS. 15A and 15B ) causes core-locking protrusions  65  to bend to a locking angle α as great as 90 degrees. However, a neck portion  36  of shorter length  38  may be required if the locking members  65  are to be bent to a greater locking angle α (e.g., 120 degrees). 
     Optionally, neck portion  36  includes a tapered tip portion  39 . The tapered tip portion  39  is an optional feature of the core  92 , but helps center the core  92  within the jacket  82  during high-speed production. In some embodiments, the tapered tip portion  39  can have a frustoconical shape, a rounded shape, or a conical shape. When core  92  lacks tapered end portion  39 , neck portion  36  can terminate at core rear end  79  with a 90-degree angle. When core  92  lacks tapered tip portion  39 , the length  38  of the neck portion  36  is generally equal to the length  38  of neck portion  36  when it does include tapered end portion  39 .  FIG. 15B  is a longitudinal sectional view of core  92  shown in  FIG. 15A . An overall length  40  of the core  92  includes the combined lengths of first portion  33 , core transition portion  35 , neck portion  36 , and axial length  37  of tapered end portion  39 . 
       FIG. 16  shows the processed jacket  160  shown in  FIG. 14  after the core  92  shown in  FIG. 15B  has been dropped or otherwise placed  420  inside it with the neck portion  36  (and tapered end portion  39 ) passing through the centralized circular space (an imaginary circle) defined between ends or corners  64  of the core-locking protrusions  65  (refer to  FIG. 13B ). At this stage, the core  92  is loosely held within the processed jacket  160  and the core  92  is supported by shoulder  31  against the ends of the core-locking protrusions  65 . An annular gap  69  exists between the neck portion  36  of the core  92  and rear sidewall  93 . Here, core  92  includes a neck portion  36  of full or long length  38 . In some embodiments, a “long” neck portion  36  has a length  38  from 0.20″ to 0.50″ depending on the type and caliber of projectile  100 . This increased length  38  may be necessary to produce a core-locking angle α from 60 to 90 degrees during the core-seating process, while a shorter neck length  38  may be required to bend core-locking protrusions  65  to a locking angle α between 90 and 120 degrees. In some embodiments, a “short” neck portion  36  has a length  38  from 0.050″ to 0.175″ depending on the type and caliber of projectile  100 . In some embodiments, a small amount of space exists between the interior rear surface  70  of the jacket  82  and the core rear end  79 . The space helps to achieve even contact between the shoulder  31  of the core  92  and the ends of the core-locking protrusions  65 . When core  92  is dropped or placed  420  into processed jacket  160 , the core-locking protrusions  65  are disposed at a 30-degree angle or other angle consistent with blade angle β when core-locking protrusions  65  are formed  410 . Placing  420  the core  92  in the jacket pre-form  150  is the first step in the component-marrying process associated with the projectile  100  having a core-locking angle α as great as 90 degrees. 
       FIG. 17  shows the processed jacket  160  and core  92  of  FIG. 16  in a partially-married configuration after a flat-ended core seating punch (not shown) has begun to deform the core  92  and bend the core-locking protrusions  65  radially inward and rearward. In some embodiments, the pressure generated within the jacket  82  during the core-seating process can exceed 35,000 pounds per square inch (psi), allowing a great deal of work to be performed in bending the core locking members  65  and deforming the core  92 . As shown, axially-oriented forces have axially compressed and radially expanded the core  92  to somewhat conform to the jacket  82 . During this process, the core shoulder  31  is deformed as it presses against the top surfaces of the core-locking protrusions  65  and bends them downwardly. Bending the core-locking protrusions  65  occurs before maximum deformation and widening occurs in the neck portion  36  of the core  92 . The sequence of events can be critical with respect to core-seating; completely filling the core-locking chamber  67  occurs after the core-locking members have been forced (bent) to their final core-locking angle α and embedded into core  92 . The delay in filling the core-locking chamber  67  provides time for the shoulder  31  to bend the core-locking protrusions  65 . As shown in  FIG. 17 , the air space  69  surrounding the now-deformed neck portion  36  of the core  92  has become narrower than that shown in  FIG. 16  since the neck portion  36  has now grown in diameter. Even though the core  92  is only partially deformed at this point, it has already forced the core-locking protrusions  65  from their initial 30-degree angle to their final 60-degree locking angle α along protrusion axis  60 . The final axial height  81  of the core-locking protrusions  65  is determined after core-locking protrusions  65  have been forced radially inward to their final locking angle α during the core-seating process. While  FIG. 17  shows only a partial seating of the core  92 , it illustrates the sequential progression involved in the second step of seating  425  the core  92  discussed below with reference to  FIG. 18 . 
       FIG. 18  shows core  92  and processed jacket  160  of  FIG. 17  in a fully-married configuration known as a cylindrical pre-form  220  after the core  92  has been fully seated  425  in the processed jacket  160 . The core seating punch (not shown) has been used to further axially compress and radially expand the core  92  to inside surface  82   b  of the processed jacket  160 , thereby further embedding core-locking protrusions  65  and filling the majority of the processed jacket  160  and locking chamber  67  with core  92  material. In some embodiments, the core-locking protrusions  65  can be radially embedded into a rear portion of the core  92  to a depth between about 0.015″ and 0.100″, depending on projectile caliber, weight and type. The annular gap  69  that existed around the deformed neck portion  36  of the core  92  in  FIG. 16  has been completely displaced by core  92  material. The final core-locking angle α of about 60 degrees shown in  FIG. 18  has been maintained due to a state of equilibrium achieved from the timing and the delay involved in filling the locking chamber  67  with core  92  material. Displacing air between the core  92  and the inside surface  82   b  of processed jacket  160  is the second step of seating  425  core in the processed jacket  160 .  FIG. 18  shows the fully-married configuration for projectiles  100  having a core-locking angle α up to 90 degrees produced in accordance with the present disclosure. 
       FIGS. 19 and 20  illustrate seating  425  the core  92  in the processed jacket  160  for projectiles having a core-locking angle α greater than 90 degrees.  FIG. 19  shows the processed jacket  160  of  FIG. 14  after core  92  configured with a shorter neck portion  36  has been dropped or placed  420  inside it with the shorter neck portion  36  and tapered end portion  39  passing through the centralized circular space defined between the core-locking protrusions  65 . At this point, the core  92  is loosely held within the processed jacket  160  and the core shoulder  31  rests against the ends of the core-locking protrusions  65 . A large annular gap  69  exists about the neck portion  36  and the tapered end portion  39  of the core  92 . As shown in this embodiment, for example, the neck portion  36  shown here is considered to be “short.” In some embodiments, this shorter neck length may be necessary in order to effectively bend the core-locking protrusions  65  to a locking angle α between 90 and 120 degrees during the core-seating process. In some embodiments, it is critical that a large amount of open space exists between base inside surface  70  of the jacket  82  and the core rear end  79 . This additional open space facilitates even contact between the core shoulder  31  and the ends of the core-locking protrusions  65 . Also, the open space delays the filling of the locking chamber  67  as core  92  material is extruded into it during seating  425  the core  92 . While placing  420  the core  92  in the jacket pre-form  150 , the core-locking protrusions  65  are disposed at a 30-degree angle or other angle consistent with blade angle β as initially formed with the dividing punch  130 . This is the first step of seating  425  the core  92  for projectiles  100  having a core-locking angle α greater than 90 degrees in accordance with the present disclosure. 
       FIG. 20  shows the processed jacket  160  and core  92  of  FIG. 19  after a flat-ended core seating punch (not shown) has begun to deform the core  92  and bend the core-locking protrusions  65  radially inward and rearward. As shown, axially-oriented forces have axially compressed and radially widened the core  92 . During this shortening process, the core shoulder  31  was deformed as it pressed against the top surfaces of the core-locking protrusions  65  and bent them downwardly. Bending of the core-locking protrusions  65  occurs before a large amount of core  92  material is extruded through the spaces  66  in the rear sidewall  93  and before maximum deformation occurs in the smaller-diameter neck portion  36  of the core  92 . In some embodiments, complete filling of the locking chamber  67  occurs after the core-locking protrusions  65  have been forced to extend along protrusion axis  60  to define final core-locking angle α. Essentially, the delayed extrusion and filling of the locking chamber  67  allows time for the core shoulder  31  to bend the core-locking protrusions  65 . As can be seen, the annular gap  69  surrounding the now-deformed neck portion  36  has become narrower than that shown in  FIG. 19  since the neck portion  36  has now grown in diameter. Even though the core  92  is only partially deformed at this point, it has already forced the core-locking protrusions  65  from their initial 30-degree angle to their final locking angle α of about 120 degrees while embedding the core-locking protrusions  65  in core  92 . The final axial height  81  of the core-locking protrusions  65  is shown after the core-locking protrusions  65  have been forced radially inward during the initial step of seating  425  the core  92 . While  FIG. 20  shows only a partial seating  425  of the core  92 , it illustrates the sequential progression involved in the second step in seating  425  the core  92  as discussed below with reference to  FIG. 21 . 
       FIG. 21  shows the processed jacket  160  and core  92  of  FIG. 20  after the core  92  has been fully seated  425  in the processed jacket  160 , resulting in cylindrical pre-form  220 ′. The core-seating punch (not shown) has further axially compressed and radially expanded the core  92  to completely fill the majority of the jacket  82 , including the locking chamber  67 , with core material  92 . The annular gap  69  that existed around the deformed neck portion  36  of the core  92  in  FIG. 20  has been completely displaced by core  92  material and core-locking protrusions  65  fully embedded into core  92 . Core-locking protrusions  65  extend along protrusion axis  60  with a final locking angle α of about 120 degrees, which has been maintained due to a state of equilibrium achieved from the delay in filling the locking chamber  67  with core  92  material. Axial compression and radial expansion of the core  92  is the second step involved in the component-marrying process of seating  425  the core  92 . 
       FIG. 22  illustrates a longitudinal cross-sectional view of an example of a profiled, fully-formed projectile  100  made in accordance with an embodiment of the present disclosure, where the core-locking protrusions  65  extend along protrusion axis  60  with a core-locking angle α of about 60 degrees. The core-locking angle α of 60 degrees was achieved (and pre-established in the cylindrical pre-form  220 ) through the use of a core  92  with a long neck portion  36  and that was fully seated  425  in the cylindrical pre-form  220  as shown for example in  FIG. 17 . The cylindrical pre-form  220  of  FIG. 18  was then forced into an ogival pointing die to form  430  the projectile  100  as shown in  FIG. 22 . 
       FIG. 23  illustrates a longitudinal cross-sectional view of an example of a profiled, fully-formed projectile  100  in accordance with an embodiment of the present disclosure, where the core-locking protrusions  65  extend along protrusion axis  60  to define a core-locking angle α of about 120 degrees. The core-locking angle α of 120 degrees was achieved (and pre-established in the cylindrical pre-form  220 ′ of  FIG. 20 ) through the use of a core  92  with a short neck portion  36  that was fully seated  425  in the cylindrical pre-form  220 ′, such as shown in  FIG. 21 . The cylindrical pre-form  220 ′ was then forced into an ogival pointing die to form  430  the projectile  100 . 
     The use of a plurality of circumferentially-spaced core-locking protrusions  65  provides an improved grip on core  92  compared to prior-art methods due to increased protrusion into core  92  by each core-locking member  65 . Core-locking protrusions  65  can be initially formed with a protrusion length as needed for core-locking protrusions  65  to embed into core  92  to the desired depth. The result is superior core-gripping ability that retains jacket  82  with core  92  on impact with a target. 
     Embodiments in accordance with the present disclosure provide an expanding projectile  100  with improved retention between the core  92  and the jacket  82  upon impact with a target. As a result, embodiments of projectile  100  have improved expansion to more effectively incapacitate a target in hunting, law enforcement, or self-defense situations. Expanding projectile  100  can be easily manufactured at low-cost in accordance with some embodiments of the present disclosure. 
       FIG. 24  illustrates an elevational view of a firearm cartridge  250  in accordance with an embodiment of the present disclosure. Cartridge  250  includes a cartridge casing  252  with a generally cylindrical shape. Cartridge casing  252  includes a head  254 , a body  256 , and a neck  258  that extends to an open mouth  260  with projectile  100  retained therein. In the embodiment shown in  FIG. 24 , neck  258  has a reduced diameter compared to body  256  as may be the case for rifle ammunition. A straight casing configuration can also be used. A quantity of propellant  262  (e.g., gunpowder) is contained within cartridge casing  252 . As shown in  FIG. 24 , cartridge  250  is configured as a rifle cartridge with a hollow point projectile  100 . Other ammunition types, casing configurations, and projectile configurations are acceptable, including pistol and rifle ammunition configured for rimfire or centerfire and having a projectile with a soft point, hollow point, and ballistic tip configurations. Numerous variations and embodiments will be apparent in light of the present disclosure. 
     The embodiments of the disclosure and the various features thereof are discussed with reference to the non-limiting embodiments and examples that are illustrated in the accompanying drawings. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of certain components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the disclosure. The examples used herein are intended merely to facilitate an understanding of ways in which the disclosure can be practiced and to further enable those of skill in the art to practice the embodiments of the disclosure. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the disclosure. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings unless otherwise noted. 
     It is understood that the disclosure is not limited to the particular methodology, devices, apparatus, materials, applications, etc., described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the disclosure. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Example methods, structures, and materials are described, although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure. 
     Those skilled in the art will appreciate that many modifications to the embodiments are possible without departing from the scope of the disclosure. In addition, it is possible to use some of the features of the embodiments described without the corresponding use of the other features. Accordingly, the foregoing description of the exemplary embodiments is provided for the purpose of illustrating the principle of the disclosure, and not in limitation thereof, since the scope of the disclosure is defined solely by the appended claims.