Abstract:
A high strength polymer-based cartridge casing includes a cartridge body, molded from a polymer, having a first end and an opposing second end, and enclosing a volume. A bullet is removably engaged with the first end and an insert is engaged to the second end. A shoulder portion is located proximate the first end and a propellant chamber formed in the volume. The propellant chamber has a first diameter proximate to the shoulder, a second diameter proximate to the insert and greater than the first diameter, and a linear slope disposed between the first diameter and the second diameter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of pending U.S. application Ser. No. 14/315,564 filed Jun. 26, 2014, which is Divisional of U.S. application Ser. No. 13/549,351 filed Jul. 13, 2012, now U.S. Pat. No. 8,763,535, which is Continuation-In-Part of pending U.S. application Ser. No. 13/350,585, filed Jan. 13, 2012, which claims priority to U.S. Provisional Application Ser. No. 61/433,170 filed Jan. 14, 2011. All applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present subject matter relates to techniques and equipment to make ammunition articles and, more particularly, to ammunition articles with plastic components such as cartridge casing bodies and bases for at least blank and subsonic ammunition. 
     BACKGROUND 
     It is well known in the industry to manufacture bullets and corresponding cartridge cases from either brass or steel. Typically, industry design calls for materials that are strong enough to withstand extreme operating pressures and which can be formed into a cartridge case to hold the bullet, while simultaneously resist rupturing during the firing process. 
     Conventional ammunition typically includes four basic components, that is, the bullet, the cartridge case holding the bullet therein, a propellant used to push the bullet down the barrel at predetermined velocities, and a primer, which provides the spark needed to ignite the powder which sets the bullet in motion down the barrel. 
     The cartridge case is typically formed from brass and is configured to hold the bullet therein to create a predetermined resistance, which is known in the industry as bullet pull. The cartridge case is also designed to contain the propellant media as well as the primer. 
     However, brass is heavy, expensive, and potentially hazardous. For example, the weight of 0.50 caliber ammunition is about 60 pounds per box (200 cartridges plus links). 
     The bullet is configured to fit within an open end or mouth of the cartridge case and conventionally includes a groove (hereinafter referred to as a cannelure) formed in the mid section of the bullet to accept a crimping action imparted to the metallic cartridge case therein. When the crimped portion of the cartridge case holds the bullet by locking into the cannelure, a bullet pull value is provided representing a predetermined tension at which the cartridge case holds the bullet. The bullet pull value, in effect, assists imparting a regulated pressure and velocity to the bullet when the bullet leaves the cartridge case and travels down the barrel of a gun. 
     Furthermore, the bullet is typically manufactured from a soft material, such as, for example only, lead, wherein the bullet accepts the mouth of the cartridge being crimped to any portion of the bullet to hold the bullet in place in the cartridge case, even though the cartridge case is crimped to the cannelure of the bullet. 
     However, one drawback of this design is that the crimped neck does not release from around the bullet evenly when fired. This leads to uncertain performance from round to round. Pressures can build up unevenly and alter the accuracy of the bullet. 
     The propellant is typically a solid chemical compound in powder form commonly referred to as smokeless powder. Propellants are selected such that when confined within the cartridge case, the propellant burns at a known and predictably rapid rate to produce the desired expanding gases. As discussed above, the expanding gases of the propellant provide the energy force that launches the bullet from the grasp of the cartridge case and propels the bullet down the barrel of the gun at a known and relatively high velocity. 
     The primer is the smallest of the four basic components used to form conventional ammunition. As discussed above, primers provide the spark needed to ignite the powder that sets the bullet in motion down the barrel. The primer includes a relatively small metal cup containing a priming mixture, foil paper, and relatively small metal post, commonly referred to as an anvil. 
     When a firing pin of a gun or firearm strikes a casing of the primer, the anvil is crushed to ignite the priming mixture contained in the metal cup of the primer. Typically, the primer mixture is an explosive lead styphnate blended with non-corrosive fuels and oxidizers which burns through a flash hole formed in the rear area of the cartridge case and ignites the propellant stored in the cartridge case. In addition to igniting the propellant, the primer produces an initial pressure to support the burning propellant and seals the rear of the cartridge case to prevent high-pressure gases from escaping rearward. It should be noted that it is well known in the industry to manufacture primers in several different sizes and from different mixtures, each of which affects ignition differently. 
     The cartridge case, which is typically metallic, acts as a payload delivery vessel and can have several body shapes and head configurations, depending on the caliber of the ammunition. Despite the different body shapes and head configurations, all cartridge cases have a feature used to guide the cartridge case, with a bullet held therein, into the chamber of the gun or firearm. 
     The primary objective of the cartridge case is to hold the bullet, primer, and propellant therein until the gun is fired. Upon firing of the gun, the cartridge case seals the chamber to prevent the hot gases from escaping the chamber in a rearward direction and harming the shooter. The empty cartridge case is extracted manually or with the assistance of gas or recoil from the chamber once the gun is fired. 
     As shown in  FIG. 1A , a bottleneck cartridge case  10  has a body  11  formed with a shoulder  12  that tapers into a neck  13  having a mouth at a first end. A primer holding chamber  15  is formed at a second end of the body opposite the first end. A divider  16  separates a main cartridge case holding chamber  17 , which contains a propellant, from the primer holding chamber  15 , which communicate with each other via a flash hole channel  18  formed in the web area  16 . An exterior circumferential region of the rear end of the cartridge case includes an extraction groove  19   a  and a rim  19   b.    
     Prior art patents in this area include U.S. Pat. No. 4,147,107 to Ringdal, U.S. Pat. No. 6,845,716 to Husseini et al., U.S. Pat. No. 7,213,519 to Wiley et al., and U.S. Pat. No. 7,610,858 to Chung. The four patents are directed to an ammunition cartridge suitable for rifles or guns and including a cartridge case made of at least a plastics material. However, each have their own drawbacks. 
     Further, the use of brass cartridges for blank or subsonic ammunition can be problematic. To reduce the velocity of the bullet exiting the cartridge, typically less propellant is used is comparison to when the bullet is traveling at its top velocity. However, the same size cartridge needs to be used so the bullet can be fired from a standard firearm. An empty space is left inside a blank or subsonic cartridge where the propellant would normally reside. To compensate, wadding (typically cotton) can be packed into the space normally filled by the propellant. This wadding can cause problems with the use of the round, including jamming the firearm and fouling silencers and/or suppressors attached to the firearm. 
     Other inventions attempting to address this issue include U.S. Pat. No. 6,283,035 to Olsen, which places an expanding insert into a brass cartridge, and U.S. Patent Application Publication No. 2003/0019385 to LeaSure which uses a heavier than standard bullet with a reduced capacity cartridge. 
     Hence, a need exists for a polymer casing that can perform as well as or better than the brass alternative. A further improvement is polymer casings that are capable of production in a more conventional and cost effective manner, i.e. by using standard loading presses. Additionally, the cartridge can provide increased performance for blank and subsonic rounds by reducing the capacity of the cartridge, but still use standard weight bullets. 
     SUMMARY 
     The teachings herein alleviate one or more of the above noted problems with the strength and formation of polymer based cartridges. 
     A high strength polymer-based cartridge casing includes an upper component of polymer, a bullet of a standard weight, a lower component of polymer, and an insert. The upper component has a shoulder portion and an upper component inner wall has a first slope extending from the shoulder. The lower component has a lower component inner wall having a second slope. The upper and lower component inner walls form a propellant chamber; and the first and second slopes reduce a volume of the propellant chamber. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds. For the high strength polymer-based cartridge casing, the standard weight of the bullet is less than one of 125%, 120%, 115%, 110%, and 105% of a maximum weight of the bullet at a particular caliber. 
     In an example, the first slope equals the second slope. In another example, the first slope does not equal the second slope. Further, the first slope and the second slope can narrow the propellant chamber as the first and second slopes progress toward the insert. Alternately, the first slope and the second slope narrow the propellant chamber as the first and second slopes progress toward the shoulder. 
     The high strength polymer-based cartridge casing can also have a first diameter of the upper component inner wall, and a second diameter of the lower component inner wall. In an example, the first diameter is greater than the second diameter. For another example, the first diameter is less than the second diameter. 
     As a result, a light weight, high strength cartridge case can be formed using standard brass cartridge loading equipment. As noted below, the present invention can be adapted to any type of cartridge, caliber, powder load, or primer. Calibers can range at least between .22 and 30 mm and accept any type of bullet that can be loaded in a typical brass cartridge. 
     Further advantages can be gained in both blank and subsonic ammunition due to the removal of wadding and the shrinking of the volume of powder based on a reduced volume in the cartridge. 
     The polymer used can be of any known polymer and additives, but the present invention uses a nylon polymer with glass fibers. Further, the portion of the cartridge that engages the extractor of the firearm can be made from heat strengthened steel for normal loads and can be a continuous molded polymer piece of the lower component for either subsonic or blank ammunition. 
     Additional advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The advantages of the present teachings may be realized and attained by practice or use of various aspects of the methodologies, instrumentalities and combinations set forth in the detailed examples discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1A  is a cross sectional view of a conventional bottleneck cartridge case; 
         FIG. 1B  is a side view of a conventional bullet; 
         FIG. 2  is a side perspective view of the outside of cartridge case of the present invention; 
         FIG. 3  is a longitudinal cross-section of the upper component of the cartridge; 
         FIG. 4  is a bottom, side, perspective, radial cross-section of the upper and lower components of the cartridge; 
         FIG. 5  is an end view of the upper component without the lower component and insert; 
         FIG. 6  is a side view of the lower component without the upper component and insert; 
         FIG. 7  is a bottom front perspective view of the lower component of  FIG. 6 ; 
         FIG. 8  is a longitudinal cross-section view of the lower component of  FIG. 6 ; 
         FIG. 9  is a side view of the insert without the upper and lower components; 
         FIG. 10  is a bottom front perspective view of the insert of  FIG. 8 ; 
         FIG. 11  is a longitudinal cross-section view of the insert of  FIG. 8 ; 
         FIG. 12  is a longitudinal cross-section view of an example of a cartridge case; 
         FIG. 13  is a top, side, perspective view of the upper component of the example; 
         FIG. 14  is a top, side perspective view of an example of an upper component of a subsonic cartridge; 
         FIG. 15  is a top, side perspective view of an upper component for a blank cartridge; 
         FIG. 16  is a longitudinal cross-section view of an example of a straight wall cartridge case; 
         FIG. 17  is a longitudinal cross-section view of the cartridge case of  FIG. 2 ; 
         FIG. 18  is a longitudinal cross-section view of an example of a tapered wall cartridge case; and 
         FIG. 19  is a longitudinal cross-section view of another example of a tapered wall cartridge case. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. 
     The present invention provides a cartridge case body strong enough to withstand gas pressures that equal or surpass the strength of brass cartridge cases under certain conditions, e.g. for both storage and handling. 
     Reference now is made in detail to the examples illustrated in the accompanying drawings and discussed below.  FIG. 2  illustrates an example of a cartridge case  100 . The cartridge case  100  includes an upper component  200 , a lower component  300 , and an insert  400 . In this example, the upper component  200  and the lower component  300  are made of a polymer, while insert  400  is made from a metal, an alloy of metals, or an alloy of a metal and a non-metal. Regardless of materials, the outer dimensions of the cartridge case  100  are within the acceptable tolerances for whatever caliber firearm it will be loaded into. 
     The polymer used is lighter than brass. A glass-filled high impact polymer can be used where the glass content is between 0%-50%, preferably between 5% and 50%. In another example the glass content can be 10%. An example of a high impact polymer without the glass content is BASF&#39;s Capron® BU50I. The insert  400  can be made of steel, and, in an example, heat treated carbon steel, 4140. The 4140 steel is further heat treated to a Rockwell “C” scale (“RC”) hardness of about 20 to about 50. However, any carbon steel with similar properties, other metals, metal alloys or metal/non-metal alloys can be used to form the insert. Heat treating a lower cost steel alloy to improve its strength is a point of distinction from the prior art, which have typically opted for more expensive alloys to deal with the strength and ductility needed for a cartridge casing application. 
     In an example, the combination of the upper component  200  and the lower component  300  are made of 10% glass-filled high impact polymer combined with the insert  400  made of heat treated 4140 steel results in a cartridge that is approximately 50% lighter than a brass formed counterpart. This weight savings in the unloaded cartridge produces a loaded cartridge of between 25%-30% lighter than the loaded brass cartridge depending on the load used, i.e. which bullet, how much powder, and type of powder used. 
     The upper component  200  includes a body  202  which transitions into a shoulder  204  that tapers into a neck  206  having a mouth  208  at a first end  210 . The upper component  200  joins the lower component  300  at an opposite, second end  212 . The lower component  300  joins the upper component  200  at a lower component first end  302  (see  FIG. 6 ). The upper  200  and lower  300  components are adhered by an ultraviolet (UV) light or heat cured resin, a spin weld, a laser weld or an ultrasonic weld. 
     At a second end  304  of the lower component  300 , the lower component is joined to the insert  400 . In one example, the upper component  200  and the lower component  300  are molded in separate molds. When the lower component  300  is molded, it is molded over the insert  400 . This is a partial molding over, since the lower component  300  does not completely cover the insert  400 . 
     A back end  402  of the insert  400  is also the rear end of the casing  100 . The insert  400  is formed with an extraction groove  404  and a rim  406 . The groove  404  and rim  406  are dimensioned to the specific size as dictated by the caliber of the ammunition. The insert  400  can be formed by turning down bar stock to the specific dimensions or can be cold formed. 
     Turning now to  FIG. 3 , a cross-section of the upper component  200  is illustrated. Because of the nature of the polymer, and the design of the neck  206  and mouth  208 , the neck  206  expands uniformly under the gas pressures formed during firing. This concentric expansion provides a smoother release of the projectile into the barrel of the firearm. The smoother release allows for a more stable flight of the projectile, providing greater accuracy and distance with the same amount of powder. 
     Moving toward the second end  212  of the upper component  200 , as the neck  206  transitions into the shoulder  204 , a sleeve  230  begins. The sleeve  230 , in this example, extends approximately to the second end  212 . The sleeve  230  can be an additional thickness to a wall  218  as is normally required for a standard cartridge, or a separately manufactured and adhered to the wall  218 . The sleeve  230  provides additional strength relative to the wall  218  of the body  202  alone. This strengthening, which is in the lateral direction, reduces bending of the upper component  200  of the cartridge case  100 . The sleeve  230  helps to keep the cartridge  100  as concentric as possible, and as noted above, concentricity is a key to accuracy. 
     The case wall  218  can have a thickness T, and the sleeve  230  can have a thickness T+, as illustrated in  FIG. 4 . Thus, the total thickness of the cartridge at the point where there is the wall  218  and sleeve  230  is the sum of T and T+. 
     The upper portion  220  of the sleeve  230  can begin in or near the neck  206  and extend over the shoulder  204 . In one example, the upper portion  220  of the sleeve  230  ends against a bullet  50  (see  FIG. 1B ) providing additional material, and thus strength, to help retain and align the bullet  50 . This thickened upper portion  220  can act like an extension of the neck  206  farther down into the shoulder. The upper portion  220  is an advantage over a brass cartridge, since brass cannot be formed in this way. Thus, the upper portion  220  can act to sit and secure the bullet in the same place in the cartridge every time. 
     The sleeve  230 , in the illustrated example of  FIGS. 3, 4 and 5 , extends almost the entire length of the body  202 . The sleeve  230  stops at an overlap portion  222  of the upper component  200 . The overlap portion  222  is the portion of the upper component  200  that engages the lower component  300 . The overlap portion  222  has a thinner wall thickness t, or a second thickness, at the second end  212  than the thickness T of the wall  218  (or T and T+) before the overlap portion  222 . The second thickness t tapers toward the outside of the upper component  200  so an outer diameter  224  of the wall  218  remains constant while an inner diameter  226  of the wall  218  increases. This allows certain examples of cartridge  100  to maintain a constant outer diameter from below the shoulder  204  to the insert  400 . The bottom end  228  of the sleeve  230  is approximately squared off to provide a square shoulder to keep the upper  200  and lower  300  components concentric during assembly. 
       FIGS. 6-8  illustrate that the lower component  300  has a tapered portion  306  starting at the lower component first end  302  and ending at a collar  308 . The slope of the tapered portion  306  approximately matches the slope of the overlap portion  222  so the two can slide over each other to engage the upper  200  and lower  300  components. The tapered portion  306  ends in a flat seat  307 . The seat  307  can have a thickness Ts which is about equal to the thickness of the wall and/or sleeve. This allows the bottom end  228  of the sleeve to sit on the seat  307  when the upper  200  and lower  300  components engage. This prevents the bottom end  228  of the sleeve  230  from being exposed. This could allow the gases to exert pressure on the bottom end  228  that can separate the upper  200  from the lower  300  component. 
     A width of the collar  308  matches the second thickness t, so that the outer diameter of the cartridge  100  remains constant past the transition point between the upper  200  and lower  300  components. Further, a thickness of the tapered portion  306  is such that at any point the sum of it with the thickness of the overlap portion  222  is approximately equal to the thickness T of the wall  218  or the thicknesses of the wall  218  and sleeve  230  (T and T+). As noted above, the tapered portion  306  and the overlap portion  222  are bonded together to join the upper  200  and lower  300  components. 
     An inner wall  310  of the lower component  300  can be formed straight. In the illustrated example in  FIG. 8 , the inner wall  310  forms a bowl shape with a hole  312  at the bottom. The hole  312  is formed as a function of the interface between the lower component  300  and the insert  400 , and its formation is discussed below. As the inner wall  310  slopes inward to form the bowl shape, it forks and forms an inner bowl  314  and an outer sheath  316 . The gap  318  that is formed between the inner bowl  314  and the outer sheath  316  is the space where a portion of the insert  400  engages the lower component  300 . As noted above, in one example, the lower component  300  is molded over a portion of the insert  400  to join the two parts. 
     Turning now to an example of the insert  400 , as illustrated in  FIG. 9 , it includes an overmolded area  408 , where the outer sheath  316  engages the insert  400  in the gap  318 . The overmolded area  408  has one or more ridges  410 . The ridges  410  allow the polymer from the outer sheath  316 , during molding, to forms bands  320  (see,  FIG. 8 ) in the gap  318 . The combination of the ridges  410  and bands  320  aid in resisting separation between the insert  400  and the lower component  300 . The resistance is most important during the extraction of the cartridge from the firearm by an extractor (not illustrated). 
     The overmolded area  408  also includes one or more keys  412 . The keys  412  are flat surfaces on the ridges  410 . These keys  412  prevent the insert  400  and the lower portion  300  from rotating in relation to one another, i.e. the insert  400  twisting around in the lower portion  300 . 
     Below the overmolded area  408 , toward the back end  402 , is a self reinforced area  414 . This portion extends to the back end  402  of the insert  400  and includes the extraction groove  404  and rim  406 . The self reinforced area  414  must, solely by the strength of its materials, withstand the forces exerted by the pressures generated by the gasses when firing the bullet and the forces generated by the extractor. In the present example, the self reinforced area  414  withstands these forces because it is made of a heat treated metal or a metal/non-metal alloy. 
       FIGS. 10 and 11  illustrate an example of the inside of the insert  400 . Open along a portion of the back end  402  and continuing partially toward the overmolded area  408  is a primer pocket  416 . The primer pocket  416  is dimensioned according to the standards for caliber of the cartridge case and intended use. A primer (not illustrated) is seated in the primer pocket  416 , and, as described above, when stricken causes an explosive force that ignites the powder (not illustrated) present in the upper  200  and lower  300  components. 
     Forward of the primer pocket  416  is a flash hole  418 . Again, the flash hole  418  is dimensioned according to the standards for the caliber of the cartridge case and intended use. The flash hole  418  allows the explosive force of the primer, seated in the primer pocket  416 , to communicate with the upper  200  and lower  300  components. 
     Forward of the primer pocket  416  and inside the overmolded area  408  is basin  420 . The basin  420  is adjacent to and outside of the inner bowl  314  of the lower component  300 . The basin  420  is bowl shaped, wherein the walls curve inwards toward the bottom. The bottom of the basin  420  is interrupted by a ring  422 . The ring  422  surrounds the flash hole  418  and extends into the basin  420 . It is the presence of the ring  422  that forms the hole  312  in the inner bowl  314  of the lower component  300 . 
     In another example of a cartridge case  120 , the sizes of the upper  200  and lower  300  components can be altered.  FIG. 12  illustrates a “small upper” embodiment with a bullet  50  in the mouth  208  of the cartridge  120 . The features of the upper  200  and lower  300  component are almost identical to the example discussed above, and the insert  400  can be identical.  FIG. 12  also illustrates the engagement between a lip  214  and the cannelure  55 . The lip  214  is a section of the neck  206  approximate to the mouth  208  that has a thicker cross section or, said differently, a portion having a smaller inner diameter than the remainder of the neck  206 . In this example, the lip  214  is square or rectangular shaped, no angles or curves in the longitudinal direction. Note, in other examples, the upper component  200  is not formed with a lip  214 . When present, the lip  214  engages the cannelure  55  formed along an outer circumferential surface of the bullet  50  when it is fitted into the mouth  208  of the cartridge casing  100 . 
       FIG. 13  shows that the neck  206  and the shoulder  204  are formed similar, but in this example, the body  202  is much shorter. Further, instead of an overlap portion  222 , there is an underskirt portion  240  that starts very close to the shoulder  204 . The underskirt portion  240  tapers to the inside of the cartridge when it engages the lower component  300 . 
     The lower component  300  in this further example, is now much longer and comprises most of the propellant chamber  340 . The tapered portion is now replaced with an outer tapered portion  342 . The outer tapered portion  342  slides over the underskirt portion  240  so the two can be joined together as noted above. The thickness of the underskirt portion  240  and the outer tapered portion  342  is approximate to the wall thickness or wall thickness and sleeve thickness. 
     The inner wall  310  is now substantially longer, can include a sleeve, but still ends in the inner bowl  314 . The engagement between the second end  304  of the lower component  300  and the insert  400  remains the same. Note that either the “small upper” or “long upper” can be used to form blank or subsonic ammunition. The walls are made thicker with the sleeve, shrinking the size of the propellant chamber  340 . Less powder can be used, but the powder is packed similarly as tight as it is for a live round because of the smaller chamber  340 . This can prevent the Secondary Explosive Effect (SEE) (below). A thick wall design for a subsonic cartridge  140  is illustrated in  FIG. 14 . 
     Illustrated is a large upper component  200  having a thicker overlap  222  portion, with a thickness t+ and an integral thickening of the wall, and/or a sleeve  230  with a thickness T+, as disclosed above. The total thickness of the wall  218  can be the sum of T+ and t+. The sleeve  230  can run the length of the upper component  200  from the mouth  208  to the start of the overlap portion  222 . The lower component  300  of a subsonic cartridge  140  can be thickened as well. The subsonic cartridge  140  can be made with the insert  400 , or the lower component  300  can be molded in one piece from polymer with the features of the insert  400 . For example, the flash hole  418 , primer pocket  416 , groove  404  and rim  406 . Alternately, the insert can also be high-strength polymer instead of the metal alloys discussed above. In this example, the lower component and the insert can be formed as one piece, and the upper component  200  can be placed on top. 
     As illustrated in  FIG. 15 , for a blank cartridge  150 , the upper component  200  can be made differently. For the blank cartridge  150 , an extension  242  can be molded to extend from the neck  206 . The extension  242  has a star-shaped cap  244  to seal off the cartridge. The cap  244  is formed partially of radially spaced fingers  246  that deform outwards during firing. Thus, the mouth  208  is molded partially shut to contain a majority of the pressures and expand open and outwards. The fingers  246  are designed, in one example, to be bend elastically and are not frangible. The object is to contain the majority of the pressures and expel anything that can act as a projectile out the barrel of the firearm. 
     When the blank cartridge  150  is formed with the “small upper” component  200  with the cap  244 . The lower component  300  can be filled with the powder and the small upper component can act as a cap to the cartridge, sealing in the powder. 
     Note that the above examples illustrate a bottleneck cartridge. Many of the features above can be used with any cartridge style, including straight wall cartridges used in pistols.  FIG. 16  illustrates an example of a straight wall cartridge  500 . The straight wall cartridge  500  is a one-piece design of all polymer. The cartridge  500  has a body  502  and a mouth  508  at a first end  510 . The walls  518  of the cartridge casing can also have a sleeve  530  along a majority of its length. 
     The sleeve  230 ,  530  is dimensioned and shaped pursuant to the requirements of each cartridge based on blank or subsonic and the particular caliber. To that end, the sleeve  530  begins set back from the first end  510  based on the depth the rear of the bullet sits in the cartridge. Further, in this example, as the walls transition into a lower bowl  514 , the sleeve  530  may extend into the bowl. This aids in the strength of a back end  512  of the cartridge  500 , since this example lacks a hardened metal insert. 
     The lower bowl  514  curves downward toward a flash hole  517  which then opens to a primer pocket  519 . Both are similar to the features described above. Further, the back end is molded to form a rim  506 . 
     Turning now to an example of a fully formed cartridge case  100 ,  FIG. 17  illustrates a cross-section of all three elements engaged together to illustrate how they interface with each other. The specific outer dimensions of the three elements and certain inner dimensions (e.g. mouth  208 , lip  214 , flash hole  418 , and primer pocket  416 ) are dictated by the caliber and type of the firearm and type of ammunition. The cartridge casing  100  of the present invention is designed to be used for any and all types of firearms and calibers, including pistols, rifles, manual, semi-automatic, and automatic firearms. 
     An exemplary construction of the upper component  200  also aids in withstanding the pressures generated. As noted above, the sleeve  230  increases the strength of the wall  218  of the upper component  200 . In the present example, the upper component  200  accounts for anywhere from 70% to 90% of the length of the cartridge casing  100 . 
     Additional examples of reduced capacity cartridge cases are illustrated in  FIGS. 18 and 19 .  FIG. 18  illustrates a lower narrowed cartridge  1000 . The lower narrowed cartridge  1000  includes an upper component  1200  of the lower narrowed cartridge, a lower component  1300  of the lower narrowed cartridge and an insert  1400  for the lower narrowed cartridge. The upper, lower, and insert  1200 ,  1300 ,  1400  are generally formed as above, except as described further below. The upper component  1200  has a mouth  1208  in which a bullet  1050  is inserted. The mouth  1208  is an opening in the neck  1206  of the upper component  1200  and can also contain a lip  1214 . The lip  1214  can engage a cannelure  1055  in the bullet  1050 . 
     Further, at least one the lip  1214  and the cannelure  1055  can be replaced with an adhesive (not illustrated). The adhesive can seal the bullet  1050  in the neck  1206  and provide a waterproofing feature, to prevent moisture from entering between the bullet  1050  and the neck  1206 . The adhesive also provides for a control for the amount of force required to project the bullet  1050  out of the cartridge  1000 . Controlling this exit force, in certain examples, can be important, since the bullet for sub-sonic ammunition is already “under powered” in relation to a standard round. 
     The bullet  1050  is a standard weight bullet for its particular caliber. The “standard weight” or common weight for a projectile varies slightly. Some examples of standard weights can include at .223 (5.56) caliber weights between 52 and 90 grains; at .308 and .300 Winchester Magnum calibers weights between 125 and 250 grains; and for .338 Lapua® Magnum caliber weights between 215 and 300 grains. This can also include standards weights for .50 caliber between 606 and 822 grains. The bullet  1050  can be less than 125% of maximum standard weight for a particular caliber. Further, the bullet can be less than 120%, 115%, 110% and 105% of the caliber&#39;s maximum standard weight. 
     The upper component  1200  can also include a shoulder  1204 . The shoulder  1204  slopes outward from the neck  1206  and then straightens out to form the upper component outer wall  1217 . The upper component  2100  can join the lower component  1300  as described above, and the lower component  1300  also can have a lower component outer wall  1317 . The upper and lower component outer walls  1217 ,  1317  can form the outer shape of the cartridge and are shaped as such to fit a standard chamber for the particular caliber. 
     Both the upper and lower components  1200 ,  1300  can have inner walls  1219 ,  1319 , respectively. The inner walls  1219 ,  1319  can form the propellant chamber  1340 , which contains the powder or other propellant to discharge the bullet  1050  from the weapon (not illustrated). The inner walls  1219 ,  1319 , in this example, can be angled to form a constant slope toward the insert  1400 . This narrows, or tapers, the propellant chamber  1340  so the diameter D 1  in the upper component  1200  is greater than the diameter D 2  closer to the insert  1400 . It can be further said that, in an example, a diameter D 1  approximate the shoulder  1204  can be greater than the diameter D 2  (in the lower component  1300 ) approximate a flash hole  1418  of the insert  1400 . In another example, diameter D 2  can equal a diameter D 3  of the flash hole  1418 . 
       FIG. 19  illustrates another example of a narrowed propellant chamber  1340 . In this example, the propellant chamber  1340  narrows toward the upper component  1200 . Thus, a diameter D 4  of the upper component  1200  is less than a diameter D 5  of the lower component  1300 . Additionally, the diameter of the lower component D 5  can be greater than the diameter D 3  of the flash hole  1418 . In one example, the diameter D 4  of the upper component  1200  is greater than or equal to a diameter D 6  of a back of the bullet  1050 . 
     In the above examples, the cartridge  1000  is described in a three-piece design (upper  1200 , lower  1300 , and insert  1400 ). Note that the cartridge  1000  can be fabricated in one-piece, all of polymer as described above, or two pieces, a polymer section and the over-molded insert  1400 . Additionally, the flash hole  1418  can also be sloped to match the slope of the inner walls  1217 ,  1317 . Further, while the above examples are described with a constant slope from the upper component  1200  to the lower component  1300 , other examples can have differing slopes between the two components  1200 ,  1300  such that one slope is steeper than the other slope. Further,  FIGS. 18 and 19  illustrate cartridges wherein the upper component  1200  is smaller than the lower component  1300 . The relative sizes of the two components  1200 ,  1300 , can be alternated or they can be equated. 
     Further, the slope of the upper component inner wall  1219  can differ from the upper component outer wall  1217 . The same can be true for the lower component inner wall  1319  differing in slope from the lower component outer wall  1317 . 
     The polymer construction of the cartridge case also provides a feature of reduced friction between the cartridge and chamber of the firearm. Reduced friction leads to reduced wear on the chamber, further extending its service life. 
     Subsonic ammunition can be manufactured using the above illustrated examples. Subsonic ammunition is designed to keep the bullet from breaking the speed of sound (approximately 340 m/s at sea level or less than 1,100 fps). Breaking the speed of sound results in the loud “crack” of a sonic boom, thus subsonic ammunition is much quieter than is standard counterpart. Typical subsonic ammunition uses less powder, to produce less energy, in the same cartridge case as standard ammunition. The remaining space is packed with wadding/filler to keep the powder near the flash hole so it can be ignited by the primer. As noted above, increasing the wall thickness eliminates the need for wadding. In one example, while a brass cartridge wall can be 0.0389″ thick, the polymer wall and sleeve can have a total thickness of 0.0879″ for the identical caliber. 
     The reduced capacity allows for a more efficient ignition of the powder and a higher load density with less powder. Low load density (roughly below 30-40%) is one of the main contributors to the Secondary Explosive Effect (SEE). SEE can destroy the strongest rifle action and it can happen on the first shot or the tenth. SEE is the result of slow or incomplete ignition of small amounts of smokeless powder. The powder smolders and releases explosive gases which, when finally ignited, detonate in a high order explosion. The better sealing effect is also important here because standard brass does not seal the chamber well at the lower pressures created during subsonic shooting. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.