Simple test, try firing his ammo in your gun. You could also put scotch tape over the head of a case and try to close the gun. Each piece of tape is about .002" then compare this to yours and see what you find out. Some factory ammo, in particular Remington and Winchester is rather slopy these days, so as you mentioned you could have a ammo problem. You might try the Federal stuff, in our shop that is what we promote and seems to be the best quality control.