Never to hijack this thread but a friend of mine that generates ammunition implies the Federal 210M primer. Why, I don't know as he was attempting not to give me proprietary details. I will use the Lee Hand Priming Device when I get about to using the Feds. Ken, the https://winchesterprimersuk95059.webbuzzfeed.com/32399863/the-fact-about-federal-no-210-large-rifle-primers-that-no-one-is-suggesting