IIRC, the Lee Site has current the listing about which primers are Alright to employ. They now seem to one out FEDERAL specially: For an example of why, load a Reside spherical inside your AR from the mag, and have it or go it about for any bit. Their clarification, https://garrettftgrb.bligblogging.com/32426988/considerations-to-know-about-federal-large-primers-for-sale