223 Rem. They encouraged CCI (more difficult primers) for all loads used in any firearm which has a free floating firing pin as being the AR does. Other wise, they reported, it issues very little and all big makes will ignite concerning the similar. ninety nine/1000 rate tags on them. https://zionbhmjg.pages10.com/not-known-facts-about-federal-m215-primers-67362473