The M27 Infantry Automatic Rifle is a variant of the HK416. The HK416 was originally developed by Heckler & Koch for U.S. special operations forces as a major product improvement of M4/M16-type carbines and rifles. Using the HK-proprietary gas piston system found on the company’s G36 rifle, the HK416 prevents propellant gases and carbon from fouling the weapon’s interior, making it the most reliable of any M4/M16 type weapon.