Years ago I was the range director for one of the service academy ranges..the one in Colorado to be exact. We were qualifiying cadets with the S&W Combat Masterpiece and military FMJ .38 Spl loads.
One cadet, who'd never shot before and didn't have any experience with what was normal recoil had a squib load on the first shot. It stopped about 1/2 the way up the barrel as near as we could determine. The 2nd, 3rd, 4th and 5th shots stacked up behind it.
The result was that they'd pushed the 1st one just about clear of the muzzle, and the last one lodged between the cylinder and the barrel, right in the forcing cone.
The resident gunsmith got a drift from his shop, then proceeded to drive all of them back down the barrel until the last one was clear of the forcing cone, allowing the cylinder to be swung out. The rest were driven down into the open frame.
Now here's the surprise...once clear, and a patch was run down the bore, we found that the entire episode had not harmed the barrel one iota. No bulge, no nothing. We reloaded the piece and shot a nicely centered group at 25 yds that measured about 2.5" as I recall.
We surmised that the cylinder gap allowed the excess pressure to dissipate before the barrel bulged!
Good guns there at S&W back then...~1967. Regards,