Belts on belted magnums will grown in diameter if the pressure is excessive for the case. There's a historical "rule of thumb" that's been promoted by gun writers in the past, that if the diameter of the belt grows more than 0.0005" in measured diameter due to a single fired shot, that the load is operating at excessively high case pressures. Note the phrase "rule of thumb".
I've measured belts grow more than .001" in a single firing in the past, while working up to detect a maximum load in my rifles.
I think a good companion "rule of thumb" is that if the primer pocket swells to the point that it won't hold fresh primers any longer within 5-7 fired shots fired at identical powder charges (with identical primers) in that same cartridge case, that the powder charge is - perhaps - excessive for that particular cartridge case.
But many of us have known guys that are happy with primer pockets surviving three firings in their cartridge case. And those guys are still alive and haven't been maimed while shooting their rifles. At least the ones I've known.
Thanks for your reply, Phorwath. I got cases sticking, and thought it was the belt, maybe, but found out this morning I got bigger issues. Doesnt appear dangerous, just aggravating. I think I have a burr on the ramp of the locking lug, on the action side. Guess I'll pull the barrel off and have a look see.