Therrin, the headspace could seriously bulge the barrel. I had it happen when a large snowflake entered the muzzle between shots. This caused,as the gunsmith put it, a compression bulge. Tell you what, I'll swap you shotguns, I'd hate to see you exlpode a nice one.
But stranger things have happened, a guy I know instructs hunter safety. Part of the course shows a shot gun exploding. He basically puts a glob of mud in the muzzle, clamps it to a shooting bench and remote fires it. One time he was using an old Remington, and it took three #2 bird shot to make it blow.
By the way, you can keep your shotgun, it a PITA to jump through the hoops in Canada.
