Luth-AR M16 .223/5.56mm A1 Threaded Stripped Upper Receiver Hard Coat Anodized Black. The M16A1 adopted in the late 1960s was designed to be a lighter and more reliable weapon than the M14 it replaced. Its development and deployment in the Vietnam War and the subsequent modifications to address early issues solidified its reputation and made it a standard issue for U.S. troops. It has since transitioned to civilian use favored by enthusiasts collectors and competitive shooters. Specifications for Luth-AR M16 .223/5.56mm A1 Threaded Stripped Upper Receiver: Manufacturer: Luth-AR Color: Black Finish: Hard Coat Anodized Fabric/Material: 7075-T6 Aluminum Caliber: 5.56mm .223 Remington Gun Make: Colt Gun Model: M16 Package Contents: Luth-AR M16 .223/5.56mm A1 Threaded Stripped Upper Receiver What firearm models does the manufacturer say Luth-AR M16 .223/5.56mm A1 Threaded Stripped Upper Receiver is compatible with? The manufacturer suggests that Luth-AR M16 .223/5.56mm A1 Threaded Stripped Upper Receiver is compatible with M16Luth-AR UR-01-M16: M16 .223/5.56mm A1 Threaded Stripped Upper Receiver Hard Coat Anodized Black