The Special Operations Forces Combat Assault Rifle (SCAR) is a modular rifle made by FN Herstal (FNH) for the United States Special Operations Command (SOCOM) to satisfy the requirements of the SCAR competition.This family of rifles consist of two main types. The SCAR-L, for “light”, is chambered in the 5.56×45mm NATO cartridge and the SCAR-H, for “heavy”, fires 7.62×51mm NATO. Both are available in Long Barrel and Close Quarters Combat variants.

The Heckler & Koch HK416 is an assault rifle designed and manufactured by Heckler & Koch. It uses the AR-15 platform, originally conceived as an improvement to the Colt M4 carbine family issued to the U.S. military, with the notable inclusion of an HK-proprietary short-stroke gas piston system derived from the Heckler & Koch G36. Military and law enforcement customers have the option of purchasing a new upper receiver, buffer and drive spring to refurbish existing AR-15s or; buy new build complete HK416s.

The M4 carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16 rifle, all based on the original AR-15 rifle designed by Eugene Stoner and made by ArmaLite. The M4 is a shorter and lighter variant of the M16A2 assault rifle, with 80% parts commonality.