Method of reconfiguring a firearm receiver system for receiving magazine-fed ammunition and belt-fed ammunition

#The disclosures herein relate generally to firearms, and more particularly to firearm upper receivers with belt-feed capability.

#Many firearms, such as assault rifles, that are commonly used in military situations are not designed by their manufacturer for use with belt-feed ammunition. Typically, such firearms are designed by their manufacturer for receiving ammunition from an ammunition magazine. The AR-15 family of firearms, including the M-16 type firearms, illustrate examples of assault rifles that are designed by their manufacturer to receive ammunition exclusively from an ammunition magazine. M-16 type firearms are a military version of the AR-15 family of firearms capable of operating in a fully automatic mode. M-16 type firearms have been manufactured by companies including, but not limited to Colt Manufacturing Company, the ArmaLite Division of Fairchild Aircraft and Engine Company, BushMaster Firearms Incorporated and Fabrique Nationale. A standard ammunition magazine for M-16 type firearms holds approximately 30 rounds of ammunition. The versatility of firearms that are intended for use in military situations and that are designed for receiving ammunition exclusively from an ammunition magazine is significantly limited.

#Some firearms, such as M-16 type firearms, may be operated in a fully automatic mode. When being operated in the fully automatic mode, firing of a round of ammunition automatically facilitates ejection of each spent round from the firing chamber and chambering of a new round into the firing chamber. As long as the trigger of such as firearm is depressed, the firearm will continue to fire until all of the ammunition is depleted.

#FIG. 1A is a side view illustrating an embodiment of a firearm having an ammunition belt attached to an upper receiver assembly.

#FIG. 1B is a side view of the firearm of FIG. 1A having an ammunition magazine attached to a lower receiver assembly, and the ammunition belt detached from the upper receiver assembly.

#FIG. 1C is a side view illustrating an embodiment of a trigger group in the lower receiver assembly of the firearm of FIG. 1A.

#An embodiment of a firearm 10 including an upper receiver assembly 12 and having an ammunition belt 14 attached to the upper receiver assembly 12 is depicted in FIG. 1A. The firearm 10 is depicted in FIG. 1B having an ammunition magazine 16 attached to a lower receiver assembly 18 of the firearm 10. As depicted in FIG. 1C, the lower receiver assembly 18 includes a lower receiver body 19 having a trigger group 20 mounted thereon. The trigger group 20 comprises a trigger 22, a hammer 24, a disconnect 26, and an automatic sear 28.

#A lower receiver assembly from an M-16 type firearm illustrates an example of the lower receiver assembly 18. M-16 type firearms are manufacturer configured for receiving ammunition exclusively from an ammunition magazine attached to their lower receiver assembly. The upper and lower receiver assemblies of an unmodified M-16 type firearm illustrate examples of as-manufactured original equipment manufacturer (OEM) upper and lower receiver assemblies.

#It is advantageous to enable a firearm configured by its manufacturer for receiving ammunition exclusively from an ammunition magazine to also receive ammunition from an ammunition belt. For firearms having a registerable lower receiver assembly, it is particularly advantageous for the an upper receiver assembly capable of supplying ammunition from an ammunition belt to be mountable on an unmodified lower receiver assembly. In this manner, such an upper receiver assembly may be legally fitted to the registerable lower receiver assembly by parties other than the manufacturer.