When I was14 years young, 180 pnds and quite gullible I once shot an old Spanish ?10 gauge(heavy and a larger bore than a 12 ga) SxS double hammer gun with a bent barrel.No doubt I shot it with the wrong technique but the experience was quite memorable.

It hurt like crazy and bruised both my shoulder and my cheek badly.After that, I don't think I shot anything bigger than a 22 rifle for a year!!