Atomic Ammunition’s 223 Remington Subsonic is unlike any .223 Rem ammunition. It is quieter than most .22 Long Rifle ammo, has virtually no felt recoil, produces the same energy and power as most 380 ACP ammunition and delivers excellent accuracy out to 100 yards from rifles with barrel twist rates of 1 in 7’’ or faster. This ammunition is not specifically designed to cycle semi or fully automatic weapons.