6.8mm spc conversion kit for dod designation m249, mk46, mk48, mga saw, and fn minimi

Abstract

Implementations of the present invention relate to apparatuses, systems, and methods for converting an M249-platform firearm to allow the use of 6.8 mm SPC ammunition therein. The conversion kit comprises an adapted barrel, barrel extension, gas port, and bolt, which are each configured to allow rapid reconfiguration of the firearm between calibers.

We claim: 
     
         1 . A kit for the conversion of an M249-platform firearm to allow the use of 6.8 mm SPC ammunition therein, the kit comprising:
 a barrel having a bore with a bore diameter greater than about 0.270 inches;   a gas port disposed in a lateral surface of the barrel, the gas port having a gas port diameter between about 0.062 inches and about 0.150 inches;   a barrel extension disposed on the barrel such that a shoulder to breach face length is between about 1.280 inches and about 1.300 inches; and   a bolt having a bolt face, the bolt face having a diameter sufficient receive a casing of SPC ammunition and to allow rotation of the casing during ejection after firing.   
     
     
         2 . The kit of  claim 1 , wherein the bore diameter is about 0.270 inches. 
     
     
         3 . The kit of  claim 1 , wherein the gas port diameter is in a range between about 0.085 inches and about 0.101 inches. 
     
     
         4 . The kit of  claim 1 , wherein the barrel extension is disposed around the barrel such that the shoulder to breach face length is about 1.296 inches. 
     
     
         5 . The kit of  claim 1 , wherein the bolt further comprises an extractor. 
     
     
         6 . The kit of  claim 5 , wherein the extractor has a hook height of about 0.358 inches. 
     
     
         7 . The kit of  claim 1 , wherein the bolt face has a diameter in a range of about 0.422 inches to about 0.460 inches. 
     
     
         8 . The kit of  claim 1 , further comprising a feed tray having a tray length about 2.3 inches. 
     
     
         9 . A method for adapting an M249-platform firearm to fire 6.8 mm SPC ammunition, the method comprising:
 replacing a standard barrel with a replacement barrel having a bore with a bore diameter greater than about 0.270 inches and a gas port having a gas port diameter between about 0.090 inches and about 0.100 inches;   replacing the standard barrel extension with a replacement barrel extension disposed on the barrel such that a shoulder to breach face length is between about 1.280 inches and about 1.300 inches; and   replacing a standard bolt with a replacement bolt having a bolt face with a diameter sufficient receive a casing of SPC ammunition and to allow rotation of the casing during ejection after firing.   
     
     
         10 . The method of  claim 9 , wherein the replacement barrel has a bore diameter about 0.270 inches. 
     
     
         11 . The method of  claim 9 , wherein the replacement barrel extension is disposed on the barrel such that the shoulder to breach face length is about 1.296 inches. 
     
     
         12 . The method of  claim 9 , wherein the replacement barrel has a gas port diameter about 0.096 inches. 
     
     
         13 . The method of  claim 9 , wherein the replacement bolt further comprises an extractor having a hook height of about 0.358 inches. 
     
     
         14 . The method of  claim 9 , further comprising replacing a feed tray having a tray length about 2.3 inches. 
     
     
         15 . A kit for the conversion of an M249-platform firearm to allow the use of 6.8 mm SPC ammunition therein, the kit comprising:
 a barrel having a bore with a bore diameter greater than about 0.270 inches;   a gas port disposed in a lateral surface of the barrel, the gas port having a gas port diameter between about 0.090 inches and about 0.100 inches;   a barrel extension disposed on the barrel such that a shoulder to breach face length is between about 1.280 inches and about 1.300 inches; and   a bolt having a bolt face, the bolt face having a diameter sufficient receive a casing of SPC ammunition and to allow rotation of the casing during ejection after firing, the bolt having an extractor with at least a portion of the extractor configured to engage the casing.   
     
     
         16 . The kit of  claim 15 , wherein the bore diameter is about 0.270 inches. 
     
     
         17 . The kit of  claim 15 , wherein the gas port diameter is about 0.096 inches. 
     
     
         18 . The kit of  claim 15 , wherein the barrel extension is disposed around the barrel such that the shoulder to breach face length is about 1.296 inches. 
     
     
         19 . The kit of  claim 15 , wherein the casing of SPC ammunition has a base diameter of about 0.422 inches. 
     
     
         20 . The kit of  claim 15 , wherein the extractor has a hook height of about 0.358 inches.