Had a guy call me with a question and I don't know the answer, but I think he is incorrect in his assumptions. Keep in mind, he can't recall specifics, and this is a shot gun (this is why I don't usually advertise in the phone book but I am in one for some reason) but he is backing out primers. He can't remember what powder he was using (because he has several powders and apparently is working up a load and didn't write down his combination) but he "feels" like the powder had too slow a burn rate so it is backing the primers out. I have never heard of this. What do you think? In a most general sense, can a powder with too slow a burn rate cause a primer to back out?