I've been negligent here, sorry. I never asked what bullet you're using. I looked at my pistol caliber seaters (I have three, not two like I said originally) and all of mine came with two seater plugs, a "flat" and "hollow" one. If your die has both styles, did you try the other one? If you're using light bullets and the "flat" seater plug it might cause your problem. I'm not trying to insult your intelligence, just trying to help you figure this out and satisfy my own curiosity.