Years ago I had that problem with my 44mag .Using less than max loads of Blue Dot I would get an occasional noticable hot one about every tenth round. I had not found anyone who could tell me why. But after I dumped that box of primers I never had the problem again !! So don't assume the primers are OK.....BTW a friend of mine had a problem with his 44 mag - he would get an occasional primer which would ignite with enough force to push the bullet into the barrel but not ignite the powder ! Threw out that box of primers - no more problems !!!