KY, I've seen the result of a 20/12 accident too.

This was a Beretta 390.

No burst, but one hell of a bulge that split the forend wood into splinters and caused minor injury.

Modern barrel steel is quite ductile and it's a lot thicker just forward of the chamber than a few inches from the muzzle where I've seen the splits from stuck wads.

"The price of good shotgunnery is constant practice" - Fred Kimble