I was told by several people on here, when I started reloading to not use the primer seat on the press, I dont know if this is true, because following their advice I bought a hand priming tool. I have never used the primer seater on my press, so I cant say if this is your problem, but I know 4 people that reload in my group of friends, and all of them use a hand priming tool, and none of us have had a misfire. Hope this helps.