Your load sounds fine. I think what is happening is you`ve got a light load that has the striker driving the cartridge forward in the chamber when it hits the primer. The primer goes off and the force of the primer pushes it back out of the pocket a bit as the case swells and stays in the forward section of the chamber. I would adjust your die to just touch the shoulder of the case when resizing. This will remove any headspace/play in the cartridge to chamber relation and prevent the case from moving ahead.
Some light loads will have enough pressure to them to stretch the case and reseat the primer when this happens. The stretching is hard on the cases and can cause premature failure if it`s excessive. The reseating also flattens the primer giving one a false sign pressures are high.
Smoke or color the case shoulder with magic marker and turn your die out 2 or three turns from touching the shell holder with the ram raised. Slowly screw the die back in a 1/4 turn at a time and size a case. When you see the shoulder being hit, the ink or smoke will smear, stop and see if the case will chamber easily in your rifle. If it`s a bit snug give the die another 1/8 turn and try again. The case should chamber freely with no effort needed but fit the chamber fully when done right. This should help case life and keep the primers seated in your cases.
