Patent Publication Number: US-2023152071-A1

Title: Metallic, non-leaded projectile for muzzle-loading firearms and methods of making and using the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional patent application Ser. No. 63/278,761, filed on Nov. 12, 2021, which is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates to ammunition in the form of projectiles designed for muzzle-loading firearms and, more particularly, to a system relying upon cylindrical, metallic, non-lead projectiles wrapped in a cloth patch and having a pair of compressible O-rings so that the projectile conforms to the barrel of a muzzle-loading firearm, as well as methods of making and using such projectiles. 
     BACKGROUND 
     Projectiles and bullets for firearms have been in use for hundreds of years. In operation, a small object is positioned at the closed end of a tubular barrel, with an explosive charge or propellant positioned proximate the object so as to force it out of the barrel at high speed toward a target. In order to improve accuracy, projectiles were typically made from comparatively malleable metals, such as lead, so that the projectile could conform to the barrel (and particularly rifled barrels), thereby causing them to fly along a more true path. 
     While improvements over the past century or so have enabled the development of self-contained cartridges that can be loaded at the breach or from chambers incorporated proximate to it, muzzle-loading firearms remain popular. Such muzzle-loading weapons require the projectile and a powder charge to be forced down the barrel from the muzzle, so the size and shape of muzzle-loading projectiles, as well as the interfacing surfaces between projectile and the barrel, need to accommodate muzzle-loading and simultaneously insure subsequent discharge of the projectile is reliable and accurate. 
     Additionally, in comparison to cannons, mortars, and other large guns, the small and portable nature of firearms (i.e., long guns, such as rifles or muskets, and handguns, such as pistols—all of which can be carried, loaded, and discharged easily by a single person) entail additional and unique considerations in comparison to heavy guns. First, owing to their inherent portability, firearms require small projectiles (usually less than 20 mm or 0.60 caliber in diameter and length that is usually less than 2.5 cm or 1 inch), meaning there are structural limitations to what can be formed/implemented on the projectile itself. Cost and ease of manufacture for the projectiles are also much larger concerns because of the relative ubiquity of small firearms. Also, because projectiles for all firearms are typically not recovered or reused, they should be made from cost-effective, sustainable, and non-toxic materials. In this regard, the use of lead has fallen out of favor, given its ability to contaminate the environment and the target itself (to the extent that target might be wild game intended for human consumption). 
     Particularly when breech-loading firearms were not as widespread, the preferred ammunition of choice for muzzle-loading firearms and long guns was a simple, round lead ball (sometimes formed by dropping molten lead and allowing it cool and form a sphere as it fell). Lead was preferred owing to its ductility, which permitted the ball to conform to the firearm barrel and/or rifling patterns when the firearm was discharged, while the spherical shapes could be loaded easily down the length of the gun barrel. Lead balls were usually wrapped in paper or other wadding to separate them from the powder/shot charge and facilitate the interface between the ball and the inner surface of the barrel as the ball moved along its length (particularly when entering and also when exiting). 
     U.S. Pat. Nos. 21,924 and 463,840 disclose patched bullets, although the former was designed specifically for breech-loading firearms. U.S. Pat. No. 7,380,505 describes a muzzle-loading firearm projectile made from copper and having a rear cavity filled with a material of low-density that separates the projectile from the powder charge. A variety of “drive” or “rotary” bands for large artillery shells are also known, such as those in U.S. Pat. Nos. 3,438,620; 3,760,736; 3,910,194; and 4,366,015; however, these cartridge-style shells incorporate a charge and are significantly larger and entail more complex manufacturing and use methods, hardware, and materials, along with larger attendant costs, so as to have little practical value in comparison to the exigencies of smaller, muzzle-loading firearm projectiles. 
     In view of the foregoing, a simple, easy to make, non-lead projectile for use in muzzle-loading firearms is needed. More particularly, an improved muzzle-loading projectile and system made from common, non-toxic metals that performs comparably to leaded munitions, in terms of conforming to the gun barrel, would be welcome. A method for making such projectiles and using them as part of a broader system are also required. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The appended drawings form part of this specification, and any information on/in the drawings is are literally encompassed (i.e., the actual stated values) and relatively encompassed (e.g., ratios for respective dimensions of parts). In the same manner, the comparative positioning and relationship of the components as shown in these drawings, as well as their function, shape, dimensions, and appearance, all inform aspects of the invention so as to be part of this written description. Unless otherwise stated, all dimensions in the drawings are with reference to inches, and any printed information on/in the drawings form part of this written disclosure. 
       In the drawings and attachments, all of which are incorporated as part of this disclosure: 
         FIG.  1 A  is a side plan view of the disclosed projectile, without the O-rings, according to various disclosed embodiments.  FIG.  1 B  is an exploded, partial cross sectional view taken along the diameter of callout A in  FIG.  1 A , illustrating the threaded bore well formed centrally therein. 
         FIG.  2    is a top plan view of the projectile of  FIG.  1 A , with the cloth patch positioned beneath the projectile. 
         FIG.  3    is a side plan view of the projective of  FIG.  1 A  including the O-rings. 
     
    
    
     DESCRIPTION OF INVENTION 
     Operation of the invention may be better understood by reference to the detailed description, drawings, claims, and abstract—all of which form part of this written disclosure. While specific aspects and embodiments are contemplated, it will be understood that persons of skill in this field will be able to adapt and/or substitute certain teachings without departing from the underlying invention. Consequently, this disclosure should not be read as unduly limiting the invention(s). 
     As used herein, the words “example” and “exemplary” mean an instance, or illustration. The words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment. The word “or” is intended to be inclusive rather an exclusive, unless context suggests otherwise. As an example, the phrase “A employs B or C,” includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). As another matter, the articles “a” and “an” are generally intended to mean “one or more” unless context suggest otherwise. 
     Generally speaking, the inventions contemplated herein meet the aforementioned needs by providing a circular, cylindrically shaped body  20  made from non-lead-containing materials, such as steel, copper, aluminium, and various known alloys of any of these metals. For the ease of producing a large number of individual projectiles, it is possible to machine the projectiles from a single piece of bar stock, which is selected based on its diameter and the availability, cost, and compatibility of its composition in regard to the manufacture and use of the projectile. The bar stock diameter should match or be machined or drawn to a size that is compatible with the calibers of muzzle-loading firearms, which is less than 1 inch and, more preferably, less than 0.75 (i.e., 0.75 caliber) or less than 0.60 inches (0.60 inches). More specifically, projectiles for firearms having muzzles of 0.45 caliber, 0.50 caliber, 0.54, and 0.58 caliber are envisioned. 
     With reference to  FIGS.  1 A through  3   , the projectile  10  is formed from a cylinder body  20  that is cut to have an axial length L that is approximately equal to or slightly larger than its diameter D, but preferably less than or equal to 110% of that diameter (i.e., for any stated or desired diameter, the appropriate length fall within 100% to 110% of the diameter). In some aspects, the length L will be 0.020 inches greater than the diameter, resulting in preferred lengths of 0.440, 0.490, 0.530, and 0.570 inches (as noted above). A taper or angled section  11  is chamfered at the leading edge  22  and trailing edge  23 . The angle of the chamfer may be between 30° and 60°, with 45° being preferred. 
     A pair of similar or identical grooves  30  are machined into the sidewall of this cylinder. Grooves  30  may include a slight radius (≤0.010 inches) connecting to retention flanges  12 ,  13  and/or body  20 . The depth of the grooves  30  should be between 0.040 and 0.12 inches in comparison to the diameter D in the main body  20 , with a depth of 0.070 to 0.010 inches preferred. The diameter D itself should be less than or equal to the caliber of the firearm, usually meaning the bar stock used for the projectile is 0.02 to 0.04 inches smaller than the inner diameter of the firearm barrel. 
     As preferred but non-limiting examples, a main body  20  has a diameter D of 0.42 inches (appropriate for 0.45 caliber firearms), while grooved section  30  has a diameter of 0.325 inches adjacent to trailing face  13 . Alternatively, a main body diameter D of 0.47 inches would entail diameters for the grooved sections  30  of 0.380 inches; body diameter D of 0.51 inches leads to grooved section diameters of 0.420 inches; and D of 0.55 inches has grooved section diameters of 0.460 inches. 
     The axial length of each of the grooves  30   a ,  30   b  should be the same, irrespective of the length L, with ranges between 0.060 and 0.100 inches being ideal and a length of 0.080 inches being preferred for both grooves  30 . Ultimately, the depth and length of the groove  30  is dictated by the dimensions of the O-rings  50 , which are disposed around the projectile  10 , as described below. 
     Each chamfered section  11  is positioned to be on the axially edges, with groove  30   a  is defined by front retention flange  12  and the body  20  and the second groove  30   b  is defined by trailing retention flange  13  and body section  20 . Thus, the chamfer section  11  occupies between 0.030 inches and 0.050 inches of total axial length (with 0.035 and 0.040 inches being preferred). In this manner, a leading retention flange  12  and a trailing retention flange  13  are created as part of the chamfered section  11 . Usually, a majority of the axial length of the section  11  (and, more preferably about 0.020 inches in all instances) will consist of the tapered/angled portion. In this manner, grooves  30  are offset from the angled section by a straight walled section aligned with the radius of the body  20  and having a radial length of between 0.010 to 0.020 inches (with 0.015 inches being preferred). 
     The diameter of the trailing retention flange  13  may be further reduced in comparison to that of the leading edge flange  12 , preferably by about 0.020 inches. This diameter reduction may occur prior to chamfering the edge  23 , meaning that the trailing face  23  will also have a slightly smaller diameter than the corresponding leading face at edge  22 . Notably, the axial length and profile of the leading retention flange  12  and trailing retention flange  13 , as well as the axial length and radial depth of the groove  30 , should remain about the same for all disclosed aspects irrespective of the original diameter D or length L of the body  20 , while all other aspects are scaled accordingly. As examples, a body  20  with a diameter D of 0.42 inches would have a flange  13  with a diameter of 0.40 inches that is reduced down to 0.325 inches at its trailing face, while a diameter D of 0.470 inches corresponds to flange  13  diameters of 0.450 inches, D of 0.510 inches to flange  13  diameters of 0.490 inches, and D of 0.550 inches to flange  13  diameter of 0.530 inches. The total axial length of the projectile  10  in all these examples would still be scaled based upon the diameter of the body  20 . 
     Ultimately, the chamfer at edges  22 ,  23  can be formed when the bar stock is cut, thereby eliminating the need for additional machining. To that end, the cuts in the bar stock can be alternated, with a slightly deeper cut used to form the edge  23  in adjacent pieces, so as to eliminate unnecessary machining (i.e., avoid the aforementioned further reduction in diameter of the flange  13 ). 
     A well  40  is bored or formed in the center of the leading edge  22 . Threads can be formed along the inner facing  42  of the well, preferably in a 10-32 or similar arrangement. The depth of the well may extend axially beyond the adjacent groove  30 , with depth of about 0.10 to 0.14 inches preferred, depending upon the length L of the projectile  10 . While a conical facing is illustrated for the well in  FIG.  2   , it will be understood that the more significant feature relates to the threaded arrangement selected for section  42 . 
     The diameter of the well  40 , as well as the particularized thread arrangement (and possibly even the depth of the well  40 ), are selected to cooperate with a threaded ramrod. In this manner, the projectile may be engaged and forcibly removed from the barrel of the firearm without the need to discharge it by inserting and rotating the ramrod to capture the projectile. 
     All specific dimensions/values provided in this application (including individual values establishing upper and lower limits of a stated range), should be interpreted in light of significant figures and afforded an additional margin of error of at least +/−0.005 inches. Further, a skilled person may discern comparative ratios and relationships between the stated values in this application, so as to allow for further scaling or the creation of additional limitations as may be appropriate to the circumstances. Any angles stated in this application include an additional margin of error of at least +/−2.5°. 
     An O-ring  50  made from a non-metallic material is provided in each groove  30 . The outer most diameter of the O-ring  50  should at least be flush with and, more preferably, extend slightly beyond the main body diameter D of projectile  10 . The material selected for the O-ring will allow it to compress when under pressurized conditions during loading and especially during discharge. In some aspects, the O-rings  50  are made of buna rubber, with the elasticity and resilience of the material—whether buna or some other rubber or polymer—insuring that the O-ring  50  can be easily fitted over the flanges  12 ,  13  and into the groove  30  without becoming subsequently displaced, except by intentional effort. 
     The presence of a pair of O-rings  50  protruding slightly beyond the diameter of the sidewall of body  20  allows the projectile  10  to conform and engage the smooth bore and/or rifled surface of the firearm barrel at two separate points. Thus, as the projectile  10  is explosively ejected from the barrel, its flight direction will be dictated by the barrel. In this regard, the O-rings  50  serve as a de facto replacement for the ductility of lead. In this manner, the projectile can be made from the non-lead metals noted above. However, other low cost, readily-available metals and alloys capable of withstanding the explosive conditions in a gun barrel could be employed. Notably, because the O-rings will be made from pliant, resilient material having a lower melting point than the metal/alloy of the projectile, it is believed that the heat generated during discharge of a firearm is sufficient to cause temporary expansion of the O-rings  50  as the projectile  10  travels down the bore, thereby further improving the engagement and interaction between the projectile and gun barrel (i.e., yielding a truer flight based on the shape and direction of the barrel). 
     In use, the projectile  10  is paired with a cloth patch  60 . The diameter of the patch  60  should exceed the diameter D of the projectile  10  by a sufficient amount to “cup” around the sidewall of body  20 . Thus, this extra diameter E for the patch  60  correlates to the length L of the body. At a minimum the extra diameter E is sufficient to allow for variation/human error as the user positions the projectile  10  on the patch  60 . Conversely, the diameter of patch  60  should not be so large as to constitute a waste of materials. 
     The thickness of patch  60  is preferably between 0.010 and 0.020 inches. Notably, because the patch  60  is folded or cupped around the entire circumference of the projectile  10 , the caliber of the firearm will be equal to the maximum diameter D of the projectile  10  plus two times the thickness of the patch (e.g., for 0.45 caliber firearm, a diameter D of 0.42 inches and a a patch with a thickness of 0.010 to 0.015 inches are appropriate/required). 
     Patch  60  may be made of cloth that is soaked or treated with a lubricant or grease so as to facilitate loading and discharging the wrapped projectile. The patch  60  actually comes into contact with the inner barrel (and any rifling provided thereon), while the O-rings  50  provide a further guide and means to keep the projectile  10  aligned during loading and discharge. Further, to the extent the O-rings  50  also compress and conform to the surface of the barrel, the patch  60  insures that the projectile  10  maintains sufficiently uniform and tight fit within the barrel bore. It will be understood that the variations between the diameter D of the projectile  10  and the intended caliber of the firearm, as well as the difference in diameter between the leading retention flange  12  and trailing retention flange  13 , are also selected to insure the entire assembly (projectile and cloth) move through the barrel. In some aspects, the patch  60  could be loosely adhered to the trailing end  23  of the projectile  10  (e.g., by a light coating of adhesive) so as to improve the ease of use and allow for the production of a ready-made projectile, although users of muzzle-loading firearms may not deem such attachment as necessary. 
     Unless noted to the contrary above, the dimensions provided herein may be scaled to the intended caliber of the projectile. These dimensions may also be adjusted to accommodate the particular machining processes and equipment used by the manufacturer. Also, while specific ranges and preferred values are provided for the dimensions, these may be adjusted proportionally according to the diameter and/or length of the body. That is, any ratio or direct or inverse relationship between these specific values should be understood as disclosed and embraced as part of the aspects of invention contemplated herein. Further, any unstated dimensions for a given component can be calculated or discerned based upon the lengths, diameters, and angles for adjacent components that might be provided herein. 
     As used herein, axial length refers to the dimensions taken along the axis of the projectile. As such, the axial length will align with the expected direction of travel, with the leading retention flange exiting the barrel of the firearm first. Components and directions identified as radial or transverse will align within a plane that is orthogonal to this axis. Thus, with reference to  FIGS.  1 A and  3   , the axial length of the projectile is visible, whereas  FIG.  3    is a radial or transverse point of view. 
     It will also be understood that the size and dimensions of the projectile  10  are of critical importance. Arbitrary and/or excessive changes to the length or diameter of the projectile will have an impact (usually negative) on the functionality of the projectile itself, in terms of accuracy, repeatability, and the like. 
     All components and materials selected herein should have sufficient structural integrity, as well as be chemically inert. Common polymers amenable to injection molding, extrusion, or other common forming processes should have particular utility for the O-rings. with grades of nitrile rubber (buna) being particularly advantageous. Preferred metallic bar stock should be machinable without undue wear/damage to equipment, yet be cost effective and readily available for mass production. To that end, all materials, equipment and methods should be selected with an eye toward workability and cost. 
     In the same manner, engagement may involve coupling or an abutting relationship. These terms, as well as any implicit or explicit reference to coupling, will should be considered in the context in which it is used, and any perceived ambiguity can potentially be resolved by referring to the drawings. 
     Although the present embodiments have been illustrated in the accompanying drawings and described in the foregoing detailed description, it is to be understood that the invention is not to be limited to just the embodiments disclosed, and numerous rearrangements, modifications and substitutions are also contemplated. The exemplary embodiment has been described with reference to the preferred embodiments, but further modifications and alterations encompass the preceding detailed description. These modifications and alterations also fall within the scope of the appended claims or the equivalents thereof