Subsonic small-caliber ammunition and bullet used in same

Abstract

A bullet comprises a casing engaging segment, a rifling leade mating segment, and a tip segment. The rifling leade mating segment has a frusto-conical shape tapering from a first diameter at a first end portion thereof to a second diameter at a second end portion thereof. The rifling leade mating segment extends from a first end portion of the casing engaging segment. The tip segment extends from the second end portion of the rifling leade mating segment. The first diameter is greater than the second diameter.

1 . A bullet, comprising:
 a casing engaging segment;   a rifling leade mating segment extending from a first end portion of the casing engaging segment, wherein the rifling leade mating segment has a frusto-conical shape tapering from a first diameter at a first end portion thereof to a second diameter at a second end portion thereof and wherein the first diameter is greater than the second diameter; and   a tip segment extending from the second end portion of the rifling leade mating segment.   
     
     
         2 . The bullet of  claim 1  wherein:
 the tip segment includes a barrel bore engaging portion extending from the second end portion of the rifling leade mating segment; and 
 the barrel bore engaging portion having a substantially cylindrical shape. 
 
     
     
         3 . The bullet of  claim 2  wherein a diameter of the barrel bore engaging portion is substantially the same as the second diameter. 
     
     
         4 . The bullet of  claim 2  wherein:
 the tip segment includes a nose portion and a barrel bore engaging portion extending between the tip portion and the second end portion of the rifling leade mating segment; 
 the barrel bore engaging portion has a substantially cylindrical shape; and 
 the nose portion has a substantially hemi-spherical shape. 
 
     
     
         5 . The bullet of  claim 4  wherein a diameter of the barrel bore engaging portion is substantially the same as the second diameter. 
     
     
         6 . The bullet of  claim 1  wherein the rifling leade mating segment has a conical taper of between about 2.4 degrees and 3.2 degrees. 
     
     
         7 . The bullet of  claim 6  wherein:
 the rifling leade mating segment has a length of about 0.2 inches; and 
 the second diameter is about 0.2 inches. 
 
     
     
         8 . A bullet, comprising:
 a jacket drawn from a copper alloy material, wherein the jacket has a casing engaging segment, a rifling leade mating segment, and a tip segment, wherein the rifling leade mating segment linearly tapers from a first diameter at a first end portion thereof to a second diameter at a second end portion thereof, wherein the rifling leade mating segment extends from the first end portion of the casing engaging segment, wherein the tip segment extends from the second end portion of the rifling leade mating segment, wherein the first diameter is greater than the second diameter, wherein the casing engagement segment defines a bearing surface portion of the jacket, wherein the bearing surface portion has a nominal thickness less than about 0.010″, and wherein the copper alloy material of at least the bearing surface portion of the jacket has a nominal hardness that is substantially greater than an as-drawn hardness of the copper alloy material of the bearing surface portion of the jacket; and   a lead core provided within the jacket   
     
     
         9 . The bullet of  claim 8  wherein:
 the tip segment includes a barrel bore engaging portion extending from the second end portion of the rifling leade mating segment; 
 the barrel bore engaging portion having a substantially cylindrical shape; and 
 a diameter of the barrel bore engaging portion is substantially the same as the second diameter. 
 
     
     
         10 . The bullet of  claim 9  wherein:
 the tip segment includes a nose portion and a barrel bore engaging portion extending between the tip portion and the second end portion of the rifling leade mating segment; 
 the barrel bore engaging portion has a substantially cylindrical shape; and 
 the nose portion has a substantially hemi-spherical shape. 
 
     
     
         11 . The bullet of  claim 10  wherein:
 the rifling leade mating segment has a taper of between about 2.4 degrees and 3.2 degrees 
 
     
     
         12 . The bullet of  claim 8  wherein the bearing surface portion of the jacket is at least partially coated with a friction-reducing material composition. 
     
     
         13 . The bullet of  claim 12  wherein the friction-reducing material composition is molybdenum disulfide. 
     
     
         14 . The bullet of  claim 13  wherein the bearing surface portion is coated in its entirety with the friction-reducing material composition. 
     
     
         15 . The bullet of  claim 8  wherein:
 the nominal hardness of the copper alloy material of at least bearing surface portion corresponds to a tensile strength of between about 32 ksi and about 44 ksi; 
 the bearing surface portion of the jacket is at least partially coated with a friction-reducing material composition; and 
 the bearing surface portion of the jacket has a thickness between about 0.004″ and about 0.008″. 
 
     
     
         16 . A round of ammunition configured for providing sufficient energy for cycling a bolt carrier in a rifle having a gas-energized bolt carrier actuation mechanism, comprising:
 a small-caliber cartridge casing configured in accordance with an original equipment manufacturer (OEM) specification for the rifle;   a bullet having a casing engaging segment, a rifling leade mating segment, and a tip segment, wherein the rifling leade mating segment has a frusto-conical shape tapering from a first diameter at a first end portion thereof to a second diameter at a second end portion thereof, wherein the rifling leade mating segment extends from the first end portion of the casing engaging segment, wherein the tip segment extends from the second end portion of the rifling leade mating segment, wherein the first diameter is greater than the second diameter, wherein the casing engagement segment defines a bearing surface portion of the bullet engaged within a bullet receiving opening of the small-caliber cartridge casing thereby forming a propellant-receiving cavity within the small-caliber cartridge casing; and   a propellant within the propellant-receiving cavity of the small-caliber cartridge casing, wherein the propellant is configured by a manufacturer thereof for being used in medium caliber ammunition.   
     
     
         17 . The round of ammunition of  claim 16  wherein:
 the bullet has a core made of a metal having lead as its major constituent component and a jacket drawn from metal having copper as its major constituent component; 
 the bearing surface portion has a nominal thickness less than about 0.010″; and 
 the copper alloy material of at least the bearing surface portion of the jacket has a nominal hardness that is substantially greater than an as-drawn hardness of the copper alloy material of the bearing surface portion of the jacket 
 
     
     
         18 . The round of ammunition of  claim 16  wherein:
 the bullet has a core made of a metal having lead as its major constituent component and a jacket drawn from metal having copper as its major constituent component; 
 a nominal thickness of the jacket is less than about 0.010″; and 
 at least the bearing surface portion of the jacket has a nominal hardness that is substantially greater than an as-drawn hardness of the jacket. 
 
     
     
         19 . The round of ammunition of  claim 16  wherein:
 the tip segment includes a barrel bore engaging portion extending from the second end portion of the rifling leade mating segment; 
 the barrel bore engaging portion having a substantially cylindrical shape; and 
 a diameter of the barrel bore engaging portion is substantially the same as the second diameter. 
 
     
     
         20 . The round of ammunition of  claim 16  wherein:
 the nominal hardness of the copper alloy material of at least bearing surface portion corresponds to a tensile strength of between about 32 ksi and about 44 ksi; 
 the bearing surface portion of the jacket is at least partially coated with a friction-reducing material composition; and 
 the bearing surface portion of the jacket has a thickness between about 0.004″ and about 0.008″.