I've been using both for years and I can't tell any difference between them. I believe that the rifle primers are slightly hotter to ignite rifle powder and the metal may be slightly heavier, but not that I've noticed. I've never had a problem buying either from any of the RFDs that I've used. If they don't know me they just check that I have reason to have them, ie, FAC. I don't remember any of them checking what was on it. You can buy primers for blank firers for stage or re-enactments without an FAC.