Automatic/semi-automatic rifle assembly for large caliber belted cartridges

Abstract

Embodiments of the present disclosure provide modifications to the AR platform operating system such that the platform now is competent to fire large caliber cartridges, including belted cartridges, providing longer range and greater barrier penetration without substantially altering the characteristic features and component inter-relationships of this platform.

1 . An automatic or semi-automatic firearm assembly configured for firing a belted cartridge, the firearm assembly comprising:
 a gas operating system for automatic action cycling;   an upper receiver assembly configured for receiving magazine-fed belted cartridges and for ejecting spent cartridge casings through an ejection port;   an elongate firing pin;   an elongate bolt carrier having a central bore, a posterior end configured to interface the firing pin, and an anterior end configured to interface a bolt assembly partially disposed within the central bore, the bolt assembly operative with the firing pin and including a bolt and a bolt extractor; and   a barrel chamber having anterior and posterior ends for receiving the belted cartridge, the barrel chamber having a wall thickness between about 0.250 to 0.350 inches, and wherein the barrel chamber includes a counter bore at its posterior end to interface the belted portion of the belted cartridge.   
     
     
         2 . The firearm assembly of  claim 1 , wherein the bolt carrier further comprises:
 an upper relief cut aperture through an outer surface of the bolt carrier, the upper relief cut aperture extending along the elongate bolt carrier from a first position intermediate along a length of the bolt carrier, to a second position located at a distance from the posterior end; and   a lower relief cut aperture through the outer surface of the bolt carrier, the lower relief cut aperture extending along the elongate bolt carrier from a third position nearer the anterior end than the first position, to a fourth position located at the distance from the posterior end, such that the lower relief cut aperture is longer than the upper relief cut aperture,   wherein the distance from the posterior end is in the range of about 0.20 inches to 3.0 inches.   
     
     
         3 . The firearm assembly of  claim 2 , wherein the lower relief cut aperture is a hammer clearance opening. 
     
     
         4 . The firearm assembly of  claim 1 , further comprising a bushing configured to interface the bolt carrier and limit travel rearward of the bolt carrier during automatic action cycling. 
     
     
         5 . The firearm assembly of  claim 1 , wherein the elongate firing pin defines a central axis, wherein the firearm assembly further comprises a charging handle inserted into a distal end of the upper receiver assembly above the central axis, the charging handle slidable parallel to the central axis into the upper receiver assembly, and wherein the charging handle is configured to engage the bolt assembly for manual action cycling to position an initial belted cartridge within the barrel chamber. 
     
     
         6 . The firearm assembly of  claim 1 , wherein the bolt extractor includes a groove having a radius in the range of about 0.260 inches to 0.270 inches. 
     
     
         7 . The firearm assembly of  claim 1 , wherein the counter bore has a chamber depth in the range of 0.0905 inches to 0.0965 inches. 
     
     
         8 . The firearm assembly of  claim 1 , wherein the counter bore has a diameter in the range of 0.530 inches to 0.535 inches. 
     
     
         9 . The firearm assembly of  claim 1 , further comprising a detachable lower assembly configured for engaging the upper receiver assembly, the lower assembly configured to have a magazine attached thereto for supplying ammunition from the magazine to the upper receiver assembly. 
     
     
         10 . An automatic or semi-automatic firearm assembly configured for firing a belted cartridge, the firearm assembly comprising:
 a gas operating system for automatic action cycling;   an upper receiver assembly configured for receiving magazine-fed belted cartridges and for ejecting spent cartridge casings through an ejection port;   an elongate firing pin;   an elongate bolt carrier having a central bore, a posterior end configured to interface the firing pin, and an anterior end configured to interface a bolt assembly partially disposed within the central bore, the bolt assembly operative with the firing pin and including a bolt and a bolt extractor;   a bushing configured to interface the bolt carrier and limit travel rearward of the bolt carrier during automatic action cycling; and   a barrel chamber having anterior and posterior ends for receiving the belted cartridge, and wherein the barrel chamber includes a counter bore at its posterior end to interface the belted portion of the belted cartridge.   
     
     
         11 . The firearm assembly of  claim 10 , wherein the bolt carrier further comprises:
 an upper relief cut aperture through an outer surface of the bolt carrier, the upper relief cut aperture extending along the elongate bolt carrier from a first position intermediate along a length of the bolt carrier, to a second position located at a distance from the posterior end; and   a lower relief cut aperture through the outer surface of the bolt carrier, the lower relief cut aperture extending along the elongate bolt carrier from a third position nearer the anterior end than the first position, to a fourth position located at the distance from the posterior end, such that the lower relief cut aperture is longer than the upper relief cut aperture,   wherein the distance from the posterior end is in the range of about 0.20 inches to 3.0 inches.   
     
     
         12 . The firearm assembly of  claim 11 , wherein the lower relief cut aperture is a hammer clearance opening. 
     
     
         13 . The firearm assembly of  claim 10 , wherein the barrel chamber has a wall thickness between about 0.250 to 0.350 inches. 
     
     
         14 . The firearm assembly of  claim 10 , wherein the elongate firing pin defines a central axis, wherein the firearm assembly further comprises a charging handle inserted into a distal end of the upper receiver assembly above the central axis, the charging handle slidable parallel to the central axis into the upper receiver assembly, and wherein the charging handle is configured to engage the bolt assembly for manual action cycling to position an initial belted cartridge within the barrel chamber. 
     
     
         15 . The firearm assembly of  claim 10 , wherein the bolt extractor includes a groove having a radius in the range of about 0.260 inches to 0.270 inches. 
     
     
         16 . The firearm assembly of  claim 10 , wherein the counter bore has a chamber depth in the range of 0.0905 inches to 0.0965 inches. 
     
     
         17 . The firearm assembly of  claim 10 , wherein the counter bore has a diameter in the range of 0.530 inches to 0.535 inches. 
     
     
         18 . The firearm assembly of  claim 10 , further comprising a detachable lower assembly configured for engaging the upper receiver assembly, the lower assembly configured to have a magazine attached thereto for supplying ammunition from the magazine to the upper receiver assembly. 
     
     
         19 . An automatic or semi-automatic firearm assembly configured for firing a belted cartridge, the firearm assembly comprising:
 a gas operating system for automatic action cycling;   an upper receiver assembly configured for receiving magazine-fed belted cartridges and for ejecting spent cartridge casings through an ejection port;   an elongate firing pin;   an elongate bolt carrier having a central bore, a posterior end configured to interface the firing pin, and an anterior end configured to interface a bolt assembly partially disposed within the central bore, the bolt assembly operative with the firing pin and including a bolt and a bolt extractor, the bolt carrier further comprising:
 an upper relief cut aperture through an outer surface of the bolt carrier, the upper relief cut aperture extending along the elongate bolt carrier from a first position intermediate along a length of the bolt carrier, to a second position located at a distance from the posterior end; and 
 a lower relief cut aperture through the outer surface of the bolt carrier configured to provide a hammer clearance opening, the lower relief cut aperture extending along the elongate bolt carrier from a third position nearer the anterior end than the first position, to a fourth position located at the distance from the posterior end, such that the lower relief cut aperture is longer than the upper relief cut aperture; and 
   a barrel chamber having anterior and posterior ends for receiving the belted cartridge, the barrel chamber having a wall thickness between about 0.250 to 0.350 inches, wherein the barrel chamber includes a counter bore at its posterior end to interface the belted portion of the belted cartridge, and wherein the overall length of the ejection port is between about 3.4 inches and about 4.5 inches.   
     
     
         20 . The firearm assembly of  claim 19 , wherein the elongate firing pin defines a central axis, wherein the firearm assembly further comprises a charging handle inserted into a distal end of the upper receiver assembly above the central axis, the charging handle slidable parallel to the central axis into the upper receiver assembly, and wherein the charging handle is configured to engage the bolt assembly for manual action cycling to position an initial belted cartridge within the barrel chamber. 
     
     
         21 . The firearm assembly of  claim 19 , further comprising a bushing configured to interface the bolt carrier and limit travel rearward of the bolt carrier during automatic action cycling. 
     
     
         22 . The firearm assembly of  claim 19 , wherein the bolt extractor includes a groove having a radius in the range of about 0.260 inches to 0.270 inches. 
     
     
         23 . The firearm assembly of  claim 19 , wherein the counter bore has a chamber depth in the range of 0.0905 inches to 0.0965 inches. 
     
     
         24 . The firearm assembly of  claim 19 , further comprising a detachable lower assembly configured for engaging the upper receiver assembly, the lower assembly configured to have a magazine attached thereto for supplying ammunition from the magazine to the upper receiver assembly. 
     
     
         25 . The firearm assembly of  claim 19 , wherein the distance from the posterior end is in the range of about 0.20 inches to 3.0 inches.