The 5.56mm M27 Infantry Automatic Rifle has remained a favorite rifle of the Marine Corps for the better part of this decade. Based on the Heckler & Koch HK416 assault rifle and adopted in 2011 to replace the M249 Squad Automatic Weapon, it’s widely considered more versatile and accurate over a longer range than the average weapon — so much so that the Corps has even discussed replacing every infantry Marine’s M4 carbine with an IAR variant in coming years.