IIRC, the Lee Web page has updated the checklist about which primers are ok to use. They now manage to single out FEDERAL exclusively: 223 Rem. They advised CCI (more durable primers) for all hundreds Employed in any firearm that has a cost-free floating firing pin as the AR does. https://large-pistol-primers-for76914.blog2learn.com/79788293/the-greatest-guide-to-federal-large-rifle-magnum-primers-215