my father in law has loaded thousands of shells and has never had the problem he had last weekend. He loaded 50 Rem 6mm (brand new remington cases) and approx 1/2 of them didnt fire. the primer had an indent in it, but not enough to fire the primer. any ideas on what could have happened as it is worrying him a bit. our thoughts, bad primers? or is it possible to seat the primer to deep? it appeared that maybe some of the primers were seated a little deeper than others? any help would be appreciated.