Originally Posted by WiskyT
The use of small pistol magnum primers would not pit your breach face. I don't know what's going on with that gun/ammo, but it is not caused by using magnum pistol primers.
It could be that his load is so low in pressure that it just doesn't seal the primer at all. I don't know for sure. Perhaps dirty pockets and a low load. To me he has wondered of the reservation with out a guide and anyone is just guessing at this point. I would go back to using the right primer and standard loads and stop fiddling around with non-standard things until he figures it out.