Atomic's Tactical Cycling Subsonic is unlike traditional high powered rifle ammunition. Unsuppressed, it is as quiet as most 22 LR and has minimal felt recoil. These relatively innocuous-sounding cartridges, with their low recoil and report, serve professionals with an alternative to much louder standard power rifle cartridges allowing faster follow up shots and better full auto accuracy with the added safety of not penetrating level 2 and higher armor worn by many law enforcement and military professionals. Atomic's Tactical Cycling Subsonic in 5.56x45mm produces similar energy and power as 9mm cartridges and delivers CQB accuracy from rifles with barrel twist rates of 1 in 7" or faster. Note: DO NOT shoot this 5.56x45mm in .223 caliber firearms.