Quote Originally Posted by tacticalj
I am having a problem with the primers working back out of the casing slightly after firing a primed round.
I assume this means you are firing a case with nothing but a primer, no powder and no bullet right? I believe what you are seeing is normal. When firing a complete cartridge the force of the primer will back it out of then primer pocket slightly and then the pressure from the main powder charge reseats it. If there is no powder or bullet, there is nothing to reseat the primer.

BTW, this phenomenon is the reason pistol cartridges loaded with wax bullets and powered by only a primer have their flash holes drilled out well oversize.

I would have the headspace checked but the protruding primer by itself is not an indication it's excessive.

Any gunsmith should have go/no-go gages for the belted magnum family of cartridges and can check the headspace for you. He may not be expert on fixing it if it's a problem but he certainly can determine if it's correct.