Not to hijack this thread but a friend of mine that produces ammunition implies the Federal 210M primer. Why, I do not know as he was striving not to present me proprietary info. I will use the Lee Hand Priming Software Once i get about to utilizing the Feds. Ken, https://winchester-250-magnum-pri34678.total-blog.com/the-best-side-of-federal-gm205m-primers-57184412