There really are only two reasons for your problem.

#1. The rifles chamber likely isn't polished properly. This is a very easy and quick fix for a gunsmith. If this is the problem your fired brass will be "frosted". It will look like shiny spots on the fired brass.

#2. It could be the ammo. It isn't all that rare to have factory ammo loaded a little hot.

If the action screw was too long it would likely be difficult to operate the bolt regardless if you had ammo in the chamber or not. You would also see a wear mark on the side of the recoil lug of the bolt.