Aahh, the oh-so-controversial AR-15, the semiauto-only civilian market version of the U.S. Armed Forces’ M16 rifle. Everybody knows the “AR” stands for “Assault Rifle,” right?

The M4-series Carbine achieves over 80% commonality with the M16A2 Rifle and replaces all M3 .45 caliber submachine guns, and selected M9 pistols and M16 rifles. The Army is pursuing a two-phase ...