If I have a gun, with barrels as thin as .020 at 24" from the breech and they look perfect, without pitting in the area, I will shoot them with sane loads. Where they are thin is just as important as how thin they are. The closer to fleshy parts, I do not want to loose, the more unlikely I will be to shoot the gun. One with thin areas in the first 20" are not high on my list of guns to shoot. It is location, location, location, with all other things being the same.
Guns fail because people shoot them. They shoot them without finding defects. They shoot them with obstructions in the bores. They shoot them with loads which to me are insane. Do that and you are tempting failure every time. But if you use reasonable precautions your risk will be very, very small. But all shooting is a risk to some degree.
I've seen several K-80's that blew up. One which I am 100% certain did so with never having seen a reloaded shell in it's life. Two month old gun, just let go. Owner has more money than I dream of and has never reloaded a single shell in his life. Must be nice. Most likely cause was determined to be the base wad of a AA factory shell becoming lodged in the bore to create an obstruction. Nobody admitted fault, nobody could prove it for 100% but that was the most likely outcome. The owner just bought a second set of barrels. Don't know what he ended up doing with the first set. Mentioned he was going to have them tested by a Lab. He does not use AA ammo anymore though.
