This is actually quite timely, last week friend called, he and friend went to range to shoot friends acr, it multifired with handloads but not factory, so as soon as I read this I forwarded it to him, ATFE has successfully prosecuted for FA, by using loads with the softest primers available in AR's, A floating firing pin with no block and a worn return spring, can set off a round, hard to do, but can happen. No body should go to jail for it, but have, even if I was an FA junkie, I would want to count on it instead of it being maybe, maybe not.