Patent Publication Number: US-2023147902-A1

Title: Firearm barrel reamer having a cartridge chamber

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates in general to the field of automatic or semi-automatic firearms having a barrel having a cartridge chamber in communication with a bore and a reamer for forming a cartridge chamber. 
     STATEMENT OF FEDERALLY FUNDED RESEARCH 
     None. 
     INCORPORATION-BY-REFERENCE OF MATERIALS FILED ON COMPACT DISC 
     None. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the invention, its background is described in connection with cartridge casing, ammunition, a reamer for forming a firing chamber and the chamber in the firearm to receive the ammunition. 
     A typical firearm includes a barrel, a receiver, and a breech block or bolt. The receiver of the weapon is connected to the barrel having a cartridge chamber and the ammunition is placed into the cartridge chamber in the receiver prior to firing. The ammunition may be loaded into the cartridge chamber manually or automatically, via a magazine. The ammunition is placed in the cartridge chamber so that the bullet faces the entrance to the barrel. The rear end of the ammunition, which houses the primer, faces the bolt or breech block which contains the firing pin and functions to close off the rear end of the ammunition so that when the ammunition is fired, the bullet is ejected from the barrel. 
     The firearm cartridge for rifles and machine guns, as well as larger caliber weapons, can be made in various calibers or sizes. The firearm cartridge is essential in determining the speed and power of the bullet once the firearm is fired. Generally, bullet speed and power can be affected by many factors including changing the dimensions of the cartridge which dictate the amount of propellant carried by the cartridge. The reliable firearm cartridge require uniformity in manufacturing (e.g., bullet seating, bullet-to-casing fit, casing strength, etc.) to produce consistent pressures within the casing during firing prior to bullet and casing separation to create uniformed ballistic performance. In addition, the chamber in which the firearm cartridge is placed must have uniform and consistent dimensions to produce uniformed ballistic performance. 
     For example, U.S. Pat. No. 8,011,301 entitled “Cartridge for a firearm” issued to Jimmie Sloan discloses a cartridge case for a firearm is formed to contain a .338 caliber bullet. The case includes a cylindrical body portion with a central aperture in the head end for receipt of a primer and a cartridge extraction groove formed around the periphery of the body portion adjacent the head end. A frustoconical shoulder portion tapers radially inwardly from the body portion and a generally cylindrical neck portion extends longitudinally from the shoulder portion. The length of the body portion is approximately 1.8813 inches and the outside diameter of the body portion at the shoulder portion is 0.5709±0.0059 inches. The length of the shoulder portion is 0.2727 inches. The length of the neck portion is 0.3381 inches and the outside diameter of the neck portion is 0.3669 inches. The case encloses a volume designed to receive an amount of propellant in a range of 82.0 grns to 97.8 grns. 
     For example, U.S. Pat. No. 9,404,719 entitled “Ammunition cartridge and chamber, and tools for making and reloading same” issued to William R. Bowers discloses a case for an ammunition cartridge including a tubular member having a central axis which includes: a head which includes, a head face which is disposed substantially perpendicular to the central axis, and an extraction groove adjacent to the head face, the extraction groove circumscribing the central axis; a body abutting the head which comprises an internal chamber, a bullet receiving end spaced from the body along the central axis, a convex curved segment abutting the body, the convex curved segment being a first circular curve having a first radius of approximately 0.0263 inches, a frustoconical segment abutting the convex curved segment, and a concave curved segment abutting the frustoconical segment, the concave curved segment being a second circular curve having a second radius of approximately 0.1049 inches. The entire contents of each of which are incorporated herein by reference. 
     For example, U.S. Patent Application Publication No. 2014/0075805 entitled “Firearm barrel having cartridge chamber preparation facilitating efficient cartridge case extraction and protection against premature bolt failure” issued to Mark C. Lame discloses a barrel to permit ease and efficiency for the extraction of spent cartridge cases from the cartridge chamber of a firearm barrel within a wide range of temperature conditions, the internal tapered surface of the body region of a cartridge chamber by establishing circumferentially spaced longitudinal straight or curved regions of the internal Surface finish to create an internal cartridge chamber geometry having gradually tapered spaced longitudinally relieved linear or spiral areas having longitudinal linear or spiral lands between each of the relieved areas. The circumferentially spaced lands develop controlled impedance to rearward cartridge case movement on cartridge firing to effectively protect the bolt and extractor mechanisms of the firearm against early failure. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a new and improved barrel, chamber and reamer to form the chamber for use with a new and improved cartridge for a firearm. 
     Another object of the invention is to provide a new and improved barrel, chamber and reamer for use with a cartridge for a firearm that maximizes bullet speed, resulting in more down range energy and distance, without substantially increasing the size of the case or cartridge. 
     The present invention provides a chambering device for a barrel of a gun comprising: a shank extending longitudinally between a front end and a rear end and having a plurality of cutting flutes disposed between the front end and the rear end; a shaft extending to the rear end of the shank and adapted to rotate the shank along an interior of the barrel to form a chamber therein, wherein the shank comprises a body region that extends to a shoulder region that transitions to a case mouth that extends to a throat connected to a free bore, wherein the body region comprises a rear diameter near the breech face of about 0.4718; and a body shoulder junction diameter of about 0.4625; wherein the shoulder region comprises a shoulder case mouth junction diameter is between 0.31 to 0.32; a breech face to lead-in bore junction length of between 2.1 to 2.2; a breech face to body-shoulder junction length of between 1.80-1.85; and a breech face to shoulder neck junction length of between 1.9-2.0. 
     In one embodiment the shoulder case mouth junction diameter is 0.3169. In one embodiment the breech face to lead-in bore junction length of about 2.2272. In one embodiment the breech face to body-shoulder junction length of about 1.8229. In one embodiment the breech face to shoulder neck junction length of about 1.9490. In one embodiment the shoulder taper angle is about 30 degrees. In one embodiment the front end has a diameter less than the diameter of the shank. In one embodiment the shaft is adapted to be matingly received within the front end of the shank to transfer rotation to the shank. In one embodiment the shank is substantially cylindrical. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures and in which: 
         FIG.  1    is a side, elevation view of a nontraditional ammunition cartridge of the present invention; 
         FIG.  2    depict a side, cross-sectional view of a nontraditional ammunition cartridges of  FIG.  1   ; 
         FIG.  3    is a perspective view of a barrel; 
         FIG.  4    depicts a weapon platform; 
         FIG.  5    is a side view of the profiles of the ammunition cartridges of  FIGS.  1  and  2   ; 
         FIG.  6    is a side view of the barrel showing the chamber designed to house the ammunition cartridges of  FIGS.  1  and  2   ; and 
         FIGS.  7   a  and  7   b    are schematic illustrations of a reamer for use in preparation of a chamber to use the ammunition cartridges of  FIGS.  1  and  2   . 
     
    
    
     It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. 
     To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims. 
     The polymeric ammunition cartridges used in the cartridge chamber of the present invention are of a caliber typically carried by soldiers in combat for use in their combat weapons and common in the sporting field. The present invention is not limited to the described caliber and is believed to be applicable to other calibers as well. This includes various small and medium caliber munitions, including 5.45 mm, 5.56 mm, 6.5 mm, 6.8 mm, 7 mm, 7.62 mm, 8 mm, 9 mm, 10 mm, 12.7 mm, 14.5 mm, 20 mm, 25 mm, 30 mm, 40 mm, .17 caliber, .22 caliber, .243 caliber, .257 caliber, .270 caliber, .277 caliber, .30 caliber, .303 caliber, .308 caliber, .338 caliber, .357 caliber, .38 caliber, .375 caliber, .40 caliber, .416 caliber, .43 caliber, .44 caliber, .45 caliber, .475 caliber, and .50 caliber ammunition, cases, cartridges and components of ammunition, cases, cartridges. The chamber can be sized and dimensioned to receive any of the calibers listed above. The ammunition and ammunition cartridge as well as the nose and base used to assemble the ammunition and the cartridge have the specific size, shape and dimensions based on the caliber and chamber of the gun in which it is chambered. The chamber and the ammunition mate such that they have the same characteristics. The specific neck, shoulder, case diameter projectile aperture, and case length match with the corresponding cartridge chamber. In other embodiments of the instant application, the ammunition and ammunition cartridge as well as the nose and base used to assemble the ammunition and the cartridge have a nonstandardized size, shape and dimensions as described and illustrated herein. In one embodiment the nonstandardized size, shape and dimensions of the ammunition results from the nose having a nonstandardized size and shape to the shoulder of the nose and to the nonstandardized size of the neck. 
       FIG.  1    illustrates an ammunition cartridge  10  having a nonstandardized size, shape and dimensions resulting from the nose  12  having a nonstandardized size and shape to the shoulder  14  of the nose and to the nonstandardized size of the neck  16  and a cartridge body  18 . As used herein the term neck is defined as the opening at the top of the cartridge where the projectile sits. In a traditional cartridge the neck is a cylindrical portion above the shoulder that supports the projectile and the opening in which the projectile is placed is referenced as the case mouth. As the instant cartridge does not have a traditional neck the shoulder transitions into the case mouth. The term neck and case mouth define the same region in the instant cartridge and may be used interchangeably herein. 
       FIG.  2    depicts a side, cross-sectional view of a polymeric cartridge  10  having a nonstandardized size, shape and dimensions resulting from the nose  12  having a nonstandardized size and shape to the shoulder  14  of the nose and to the nonstandardized size of the neck  16 . A polymeric cartridge  10  suitable for use with high velocity rifles is shown manufactured with a nose  12  and a cartridge body  18  forming a powder chamber  20 . The nose  12  includes a projectile aperture  22  that is in communication with a neck  16  that is in communication with a shoulder  14  that extends to a body coupler  24 . The body coupler  24  mates to the body  18  a nose joint  26 . The body coupler  24  may have various configurations including lap joints half lap joints and overlapping joints. The illustrated joint includes a relative flat surface  30  that mates to the nose coupler  28  at the top of the cartridge body  18 . A lip  32  is positioned in communication with the flat surface  30  to contact the cartridge body  18 . 
     In other embodiments the flat surface  30  may be sloped, angled or having an alignment aid that mates a corresponding feature on the cartridge body  18  to locate and align the nose  12 . The cartridge body  18  extends a side wall  34  from the nose joint  26  toward a base end  36 . A projectile (not shown) may be inserted into the projectile aperture  22 . The polymeric cartridge  10  has a substantially cylindrical open-ended polymeric nose  12  extending from the projectile aperture  22  rearward to body coupler  24 . Body coupler  24  is shown as an overlapping joint but may also be configured as a male element in alternate embodiments of the invention. The nose  12  has a shoulder  14  forming chamber neck  16 . The nose  12  typically has a wall thickness that is thickened to accept and contact the projectile. The cartridge body  38  is connected to the nose  12  at the nose joint  26  by mating the body coupler  24  to the nose coupling element  40  of the cartridge body  38 . 
     The cartridge body  38  extends to and overmolds a primer insert  42  to complete the bottom of the polymeric cartridge  10 . The primer insert  42  includes a coupling element  44  extending from an insert bottom surface  46  that is opposite an insert top surface  48 . When contacted the polymer overmolding interlocks with the coupling element  44 , through the coupling element  44  that extends with a taper to a smaller diameter at the tip  56  to form a physical interlock between the primer insert  42  and the side wall  34 . Located in the insert top surface  48  is a primer recess  50  that extends toward the insert bottom surface  46 . A primer flash hole  52  is located in the primer recess  50  and extends through the insert bottom surface  46  into the powder chamber  20 . The coupling element  44  extends the polymer through the primer flash aperture  52  to form a primer flash hole  54  while retaining a passage from the insert top surface  48  through the bottom surface  46  and into the powder chamber  20  to provide support and protection about the primer flash hole  54 . A groove  56  is positioned around the primer flash aperture  52  in the primer recess  50  to accept the polymer overmolding once it extends through the primer flash aperture  52  to form a primer flash hole  54 . The primer insert  42  also has an extraction flange  58  positioned about the insert top surface  48  at the bottom of the polymeric cartridge  10 . The primer insert  42  includes the primer recess  50  formed in the insert top surface  48  for ease of insertion of the primer (not shown). The primer recess  38  is sized so as to receive the primer (not shown) in an interference fit during assembly. A primer flash hole  54  communicates through the insert bottom surface  46  of the primer insert  42  into the powder chamber  20  so that upon detonation of primer (not shown) the powder in powder chamber  20  will be ignited. 
     The nose  12 , the side wall  34  and primer insert  42  define the interior of powder chamber  20  in which the powder charge (not shown) is contained. The interior volume of powder chamber  20  may be varied to provide the volume necessary for complete or partial filling of the powder chamber  20  by the propellant chosen so that a simplified volumetric measure of propellant can be utilized when loading the cartridge. Either a particulate or consolidated propellant can be used. 
     Projectile (not shown) is held in place within projectile aperture  22  by an interference fit. Mechanical crimping of the projectile aperture  22  can also be applied to increase the bullet pull force. The bullet (not shown) may be inserted into place following the completion of the filling of powder chamber  20 . Projectile (not shown) can also be injection molded directly onto the projectile aperture  22  or may be secured by welding or bonding together using solvent, adhesive, spin-welding, vibration-welding, ultrasonic-welding or laser-welding techniques. The welding or bonding increases the joint strength so the casing can be extracted from the hot gun casing after firing at the cook-off temperature. 
     The nose  12  and can then be welded or bonded together using solvent, adhesive, spin-welding, vibration-welding, ultrasonic-welding or laser-welding techniques. The welding or bonding increases the joint strength so the casing can be extracted from the hot gun casing after firing at the cook-off temperature. An optional first and second annular grooves (cannelures) may be provided in the bullet-end in the interlock surface of the male coupling element to provide a snap-fit between the two components. The cannelures formed in a surface of the bullet at a location determined to be the optimal seating depth for the bullet. Once the projectile (not shown) is inserted into the projectile aperture  22  to the proper depth to lock the bullet in its proper location. One method is the crimping of the entire end of the casing into the cannelures. 
     Referring to  FIG.  3   , the barrel  60  may include a breech end  62  and a muzzle end  64 . The breech end  62  may include a breech (i.e., a chamber opening)  66  and a surrounding breech face  68 . Areas of the barrel  164  adjacent to muzzle end  64  may be threaded  70  for receiving a flash hider, compensator, suppressor, or other suitable tactical accessory or part. Although, the radial dimension of the barrel&#39;s exterior surface  72  may vary along the length of the barrel, the barrel&#39;s exterior surface may have generally constant radial dimension. Spaced from the breech end, however, may be a circumferential ring  74  that may be formed integrally with the barrel. The circumferential ring  74  may be a locking ring that may be used to secure the barrel  60  to an upper receiver of the firearm. 
       FIG.  4    depicts a weapon platform  76  that is configured for 6.8 mm ammunition. The barrel  60  of the AR-15/M4 weapon platform, however, may be chambered for the ammunition cartridge of  FIGS.  1  and  2   . The barrel  60  may be configured for straight blowback operation. The weapon platform  76  may be capable of semi-automatic and full automatic modes. 
       FIG.  5    is a side view of the profiles of the ammunition cartridges of  FIGS.  1  and  2   . The ammunition cartridge chamber that utilizes the polymeric cartridge  100  of  FIGS.  1  and  2    may have nominal dimensions intended to establish a standard cartridge type. Variations from the nominal dimensions may be tolerated by limited amounts. For example, diameters in  FIG.  5    may have a tolerance of between +0.020 and −0.020 inch which means each and every value from +0.020 to −0.020, except as otherwise noted. Below are an exemplary set of nominal dimensions and tolerances for the standard cartridge type of  FIGS.  1  and  2   . The polymeric cartridge  10  has an Extraction groove thickness  102  (L eg ) of 0.065±0.020 and an Overall Rim thickness  104  (L RMT ) of 0.054±0.020 with a Rim thickness  106  (L RM ) 0.410±0.020. The Rim diameter  108  (D RIM ) is 0.473±0.020 and the diameter of the Head Face/Extraction groove  110  (D HF/EG ) is 0.405±0.020. The length from the extractor the head face to the body  112  (L HFB ) is 0.200±0.020. The polymeric cartridge  100  has a Base diameter  114  (D B ) of 0.4705±0.020 and a nose joint diameter  116  (D NJ ) of 0.4636±0.020 with a Cartridge Body Length  118  (L CB ) of 1.500±0.020 from the 0.200 from the head face to the Nose Joint. The polymeric cartridge  100  has an axial length from head face to base-shoulder junction  120  (L HBSJ ) of 1.8225±0.020 and a base-shoulder junction diameter  122  (D BSJ ) of 0.4630±0.020. The polymeric cartridge  100  has an axial length from head face to mid-shoulder  124  (L HMS ) of 1.8840±0.020 and a diameter at the mid-shoulder  126  (D ms ) of 0.392±0.020. The polymeric cartridge  100  has an axial length from head face to shoulder-neck junction  128  (L HSNJ ) of 1.9530±0.020. As the polymeric cartridge  100  has a shoulder-neck junction diameter  130  (D SNJ ) of 0.318±0.020. The axial length from head face to shoulder-neck junction  128  (L HSNJ ) is the same as the case length  134  (L CL ) of 1.9530±0.020. The total cartridge length  136  (L TC ) is between 2.685 and 2.810±0.20. The polymeric cartridge  100  has a radius of circular curve, convex segment  138  (round) (R 1 ) of 0.140±0.020 and a radius of circular curve, concave segment  140  (fillet) (R 2 ) of 0.006±0.020. The polymeric cartridge  100  has a shoulder taper angle  142  (α 1 ) of 30°±3 and a head taper angle  144  (α 2 ) of 36°±6. 
     The ammunition cartridge  100  of  FIGS.  1  and  2    may have nominal dimensions intended to establish a standard cartridge type and these cartridge dimensions will dictate the chamber dimensions defined in the barrel. As a result, the chamber in the barrel will have dimensions that are slightly larger than the dimensions of the ammunition cartridge to accommodate the ammunition cartridge  100 . Thus the dimensions of the chamber may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 percent more than the nominal dimensions of the ammunition cartridge. 
     
       
         
           
               
            
               
                   
               
               
                 Nominal Dimensions for Exemplary Cartridge 
               
            
           
           
               
               
               
               
            
               
                 Description 
                   
                 Dimension 
                 Tolerance± 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Extraction groove thickness 
                 102 
                 L EG   
                 0.065 
                 0.020 
               
               
                 Overall rim thickness, 
                 104 
                 L RMT   
                 0.054 
                 0.020 
               
               
                 Rim thickness 
                 106 
                 L RM   
                 0.410 
                 0.020 
               
               
                 Rim diameter 
                 108 
                 D RIM   
                 0.473 
                 0.020 
               
               
                 Axial length from head face to extraction groove 
                 110 
                 D HF/EG   
                 0.405 
                 0.020 
               
               
                 Axial length from the head face to the body 
                 112 
                 L HFB   
                 0.200 
                 0.020 
               
               
                 Diameter at the base 
                 114 
                 D B   
                 0.4705 
                 0.020 
               
               
                 Diameter of the cartridge body 
                 116 
                 D cb   
                 0.4636 
                 0.020 
               
               
                 Axial length from of the cartridge body 
                 118 
                 L CB   
                 1.500 
                 0.020 
               
               
                 Axial length from the head face to the shoulder 
                 120 
                 L HBSJ   
                 1.8225 
                 0.200 
               
               
                 Diameter at the base-shoulder junction 
                 122 
                 D BSJ   
                 0.4630 
                 0.020 
               
               
                 Axial length from the head face to the mid-shoulder 
                 124 
                 L HMS   
                 1.884 
                 0.020 
               
               
                 Diameter at the mid-shoulder 
                 126 
                 D ms   
                 0.392 
                 0.020 
               
               
                 Axial length from the head face to the neck 
                 128 
                 L HSNJ   
                 1.9530 
                 0.020 
               
               
                 Diameter at the shoulder-neck junction 
                 130 
                 D SNJ   
                 0.318 
                 0.020 
               
               
                 Axial case length 
                 134 
                 L CL   
                 1.9530 
                 0.020 
               
               
                 Axial cartridge length 
                 136 
                 L TC   
                 2.685-2.81 
                 0.200 
               
               
                 Radius of circular curve, convex segment (round) 
                 138 
                 R1 
                 0.140 
                 0.020 
               
               
                 Radius of circular curve, concave segment (fillet) 
                 140 
                 R2 
                 0.006 
                 0.020 
               
               
                 Shoulder taper angle 
                 142 
                 α 1   
                 30° 
                 3 
               
               
                 Head taper angle 
                 144 
                 α 2   
                 36° 
                 6 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG.  6   , the barrel  60  may include a breech face  200 , a breech  202  that provides access to the chamber  204  that extends to a bore  206 . The chamber  204  may be configured and dimensioned in accordance with  FIG.  5   , and thus may include a profile that comprises a body segment  208 , a shoulder segment  210 , a neck segment  212 , a throat segment  214 , a free bore segment  213  and a lead in segment  216  including grooves (not shown). The barrel  60 , however, may include an optional tapered feed section (not shown) disposed between the breech face  200  and the body segment  208  of the chamber  204 . The feed section (not shown) may facilitate loading of ammunition cartridges into the chamber due to the increased diameter of the feed section (not shown) at the breech  202 . The barrel  60  includes a breech face  200  that extends to a chamber  208  which has a chamber diameter 0.200 from the bolt face  218  (D NBF ) of 0.4718±0.020 and a chamber diameter near the shoulder  220  (D NS ) of 0.4636±0.020. In the chamber  208 , the diameter at the body shoulder junction  221  (D BSJ ) is 0.4629±0.020 with the diameter at the shoulder mid-point  222  (D SM ) 0.392±0.020 and the diameter at the shoulder neck junction  224  (D SNJ ) is 0.3169±0.020. The diameter at the throat neck junction  223   a  (D TNJ ) is 0.2896±0.020 and the diameter at the throat free-bore junction  223   b  (D TFJ ) is 0.2778±0.020 and the diameter at the free-bore lead-in junction  223   c  (D FLJ ) is 0.2778±0.020. The bore diameter  225  (D B ) is 0.270±0.020 and the groove diameter  226  (D BG ) is 0.277±0.020. 
     The chamber  208  has a case length  227  (L NBFSJ ) from the 0.20 from the breech face  200  to the body shoulder junction of 1.500±0.020. The chamber  208  has a case length  228  (L BSJ ) from the breech face  200  to the body shoulder junction of 1.8229±0.020 and a mid shoulder length  230  (L BMS ) from the breech face  200  to the mid-shoulder of between 1.884 to 1.894±0.020 with a length from the breech face  200  to the shoulder neck junction  232  (L BSNJ ) of 1.9490±0.020. The chamber  208  has a case length  229  (L BTFJ ) from the breech face  200  to the throat free-bore junction is 2.066±0.020. The chamber  208  has a case length  231  (L BFLJ ) from the breech face  200  to free-bore lead-in junction is 2.206±0.020. The chamber  208  has a case length  233  (L BSJ ) from the breech face  200  to lead-in bore junction is 2.355±0.020. The chamber  208  has a Radius of concave circular curve  234  (R 1 ) of 0.140+0.030 and a Radius of convex circular curve  236  (R 2 ) of 0.014 to 0.08+0.020. The chamber  208  has a shoulder taper angle  238  (α 1 ) of 30°±3. 
     
       
         
           
               
            
               
                   
               
               
                 Nominal Dimensions for Exemplary Cartridge Chamber 
               
            
           
           
               
               
               
               
            
               
                 Description 
                   
                 Dimension 
                 Tolerance± 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Chamber diameter near the breech face 
                 218 
                 D NBF   
                 0.4718 
                 0.020 
               
               
                 Chamber diameter near the shoulder 
                 220 
                 D NS   
                 0.4636 
                 0.020 
               
               
                 Chamber diameter at the body shoulder junction 
                 221 
                 D BSJ   
                 0.4629 
                 0.020 
               
               
                 Chamber diameter at the shoulder mid-point 
                 222 
                 D SM   
                 0.3920 
                 0.020 
               
               
                 Chamber diameter at the shoulder neck junction 
                 224 
                 D SNJ   
                 0.3169 
                 0.020 
               
               
                 Chamber diameter at the throat neck junction 
                  223a 
                 D TNJ   
                 0.2896 
                 0.020 
               
               
                 Chamber diameter at the throat free bore junction 
                  223b 
                 D TFJ   
                 0.2778 
                 0.020 
               
               
                 Chamber diameter at the free bore lead injunction 
                  223c 
                 D FLJ   
                 0.2778 
                 0.020 
               
               
                 Chamber diameter of the bore 
                 225 
                 D B   
                 0.2700 
                 0.020 
               
               
                 Diameter of the groove 
                 226 
                 D BG   
                 0.2770 
                 0.020 
               
               
                 Axial length from near breech face to the body shoulder junction 
                 227 
                 L NBFSJ   
                 0.1500 
                 0.020 
               
               
                 Axial length from breech face to body-shoulder junction 
                 228 
                 L BSJ   
                 1.8229 
                 0.020 
               
               
                 Axial length from breech face to mid-shoulder 
                 230 
                 L BMS   
                 1.884-1.894 
                 0.020 
               
               
                 Axial length from breech face to the throat free-bore junction 
                 229 
                 L BTFJ   
                 2.066 
               
               
                 Axial length from breech face to free-bore lead-in junction 
                 231 
                 L BFLJ   
                 2.206 
               
               
                 Axial length from breech face to lead-in bore junction 
                 233 
                 L BSJ   
                 2.355 
               
               
                 Axial length from breech face to shoulder neck junction 
                 232 
                 L BSNJ   
                 1.9490 
                 0.020 
               
               
                 Radius of circular curve, convex segment (round) 
                 234 
                 R 1   
                 0.140 
                 0.020 
               
               
                 Radius of circular curve, concave segment (fillet) 
                 236 
                 R 2   
                 0.014-0.008 
                 0.020 
               
               
                 Radius of circular curve, convex segment (round) 
                 234 
                 R 3   
                 0.005 
                 0.020 
               
               
                 Shoulder taper angle 
                 238 
                 α1 
                 30° 
                 3 
               
               
                   
               
            
           
         
       
     
     Although the body segment  208  may be shorter in length than disclosed, the diameter D BSJ  at the base-shoulder junction may be positioned at the same distance L BSJ  from the breech face  200 . Similarly, the chamber  204  may have the same headspace dimensions (i.e., Axial length from breech face  200  to shoulder neck junction L BSNJ  and diameter at the shoulder neck junction D SNJ ) and shoulder geometry as disclosed in  FIG.  5   . Additionally, the neck segment  212  and throat segment  214  may be configured and dimensioned as necessary. 
       FIGS.  7   a  and  7   b    are schematic illustrations of a reamer for use in preparation of a chamber to use the ammunition cartridges of  FIGS.  1  and  2   . The reamer  300  is illustrated that is specifically designed to ream or form a firearm chamber compatible with cartridge illustrated in  FIGS.  1  and  2   . The values listed in  FIG.  7    may be 10% larger or 10% smaller allow for tolerances. The dimensions listed may also be ±0.02. It will be noted that the chamber has dimensions slightly larger than an unfired in  FIGS.  1  and  2   . When cartridge is fired in the chamber formed with reamers  300  the fired dimensions set forth above are achieved. 
     
       
         
           
               
            
               
                   
               
               
                 Nominal Dimensions for Exemplary Chamber Reamer 
               
            
           
           
               
               
               
               
            
               
                 Description 
                   
                 Dimension 
                 Tolerance± 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Reamer diameter near the breech face 
                 318 
                 D NBF   
                 0.4718 
                 0.020 
               
               
                 Reamer diameter at the body shoulder junction 
                 321 
                 D BSJ   
                 0.4625 
                 0.020 
               
               
                 Reamer diameter at the shoulder mid-point 
                 322 
                 D SM   
                 0.3920 
                 0.020 
               
               
                 Reamer diameter at the shoulder neck junction 
                 324 
                 D SNJ   
                 0.3169 
                 0.020 
               
               
                 Reamer diameter at the throat free bore junction 
                  323b 
                 D TFJ   
                 0.2778 
                 0.020 
               
               
                 Reamer diameter at the free bore lead in junction 
                  323c 
                 D FLJ   
                 0.2690 
                 0.020 
               
               
                 Axial length from breech face to body-shoulder junction 
                 328 
                 L BSJ   
                 1.8229 
                 0.020 
               
               
                 Axial length from breech face to mid-shoulder 
                 330 
                 L BMS   
                 1.887-1.884 
                 0.020 
               
               
                 Axial length from breech face to the throat free-bore junction 
                 329 
                 L BTFJ   
                 2.021 
                 0.020 
               
               
                 Axial length from breech face to free-bore lead-in junction 
                 331 
                 L BFLJ   
                 2.189 
                 0.020 
               
               
                 Axial length from breech face to lead-in bore junction 
                 333 
                 L BSJ   
                 2.2272 
                 0.020 
               
               
                 Axial length from breech face to shoulder neck junction 
                 332 
                 L BSNJ   
                 1.9490 
                 0.020 
               
               
                 Radius of circular curve, convex segment (round) 
                 334 
                 R 1   
                 0.140 
                 0.020 
               
               
                 Radius of circular curve, concave segment (fillet) 
                  336a 
                 R 2   
                 0.014-0.008 
                 0.020 
               
               
                 Radius of circular curve, concave segment (fillet) 
                  336b 
                 R 3   
                 0.020-0.005 
                 0.020 
               
               
                 Shoulder taper angle 
                 338 
                 α1 
                 30° 
                 3 
               
               
                   
               
            
           
         
       
     
     The reamer  300  may be configured and dimensioned to form the chamber illustrated in  FIG.  6   . The reamer  300  has a chamber diameter at the chamber&#39;s bolt face end  318  (D NBF ) of 0.4718±0.020. The reamer  300  has a diameter at the body shoulder junction  321  (D BSJ ) is 0.4625±0.020 with the diameter at the shoulder mid-point  322  (D SM ) 0.392±0.020 and the diameter at the shoulder neck junction  324  (D SNJ ) is 0.3169±0.020. The diameter at the throat free-bore junction  323   b  (D TFJ ) is 0.2778±0.020 and the diameter at the free-bore lead-in junction  323   c  (D FLJ ) is 0.2690±0.020. 
     The reamer  300  has a case length  328  (L BSJ ) from the breech face region to the body shoulder junction of 1.8229±0.020 and a mid shoulder length  330  (L BMS ) from the breech face region to the mid-shoulder of between 1.887 to 1.884±0.020 with a length from the breech face region to the shoulder neck junction  332  (L BSNJ ) of 1.9490±0.020. The reamer  300  has a case length  329  (L BTFJ ) from the breech face region to the throat free-bore junction is 2.021±0.020. The reamer  300  has a case length  331  (L BFLJ ) from the breech face region to free-bore lead-in junction is 2.189±0.020. The reamer  300  has a case length  333  (L BSJ ) from the breech face region to lead-in bore junction is 2.2272±0.020. The reamer  300  has a Radius of concave circular curve  334  (R 1 ) of 0.140+0.030 and a Radius of convex circular curve  236   a  (R 2 ) of 0.010+0.020. Radius of circular curve  236   b  of 0.020+0.020. The reamer  300  has a shoulder taper angle  238  (α 1 ) of 30°±3. 
     It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims. 
     All publications and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
     The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects. 
     As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. 
     The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context. 
     All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.