The SR-47 is a modern assault rifle based on the AR-15 family of rifles created by Knight's Armament Company for USSOCOM. Unlike the majority of guns based around ArmaLite design, the SR-47 is essentially an AR-15 that fires the Soviet 7.62×39mm round from AK-47 magazines, which explains the "47" in the gun's name. The rifle was created after soldiers on long missions in Operation Enduring Freedom complained of running out of 5.56×45mm NATO ammunition for their M4 carbines but having plenty of captured AK-47 magazines.[citation needed] The SR-47 is basically an M4 that will accept standard AK-47 magazines rather than NATO STANAG M16/M4 mags, along with other minor modifications common to KAC's designs.