Not to hijack this thread but a friend of mine that provides ammunition implies the Federal 210M primer. Why, I do not know as he was hoping not to give me proprietary data. I'll use the Lee Hand Priming tool After i get all over to using the Feds. Ken, https://federal-match-ar-primers69023.blogproducer.com/38605781/5-simple-statements-about-federal-205-primers-for-ar-15-explained