Happened to me once also and like mentioned above i believe it was from wet shells. Knocked me on my a** the shells where Win. but like i said im sure that moisture was involved.

I've seen guns blow up cause of this problem. If ever in doubt if shells are either old or have been wet, make sure they are the last of three to be shot in succession or are thrown away. Sometimes older shells and ones that have gotten wet will go bang but not KABANG and will leave the wad jammed in the barrel.

Anyone know what would happen if you were using a pump and ejected the shell before it went off and then it went off on the ground/bottom of boat, inside your waders?

pretty much snap crackle without the pop

No thanks.

With me the shell just went poof and the BB's rolled out the end of the barrel with some unspent powder. I thought huh that was interesting. That was the only time it happened in 22 years of hunting ducks.

fnf

Had a couple of weird things happen like this. While sighting in for turkey, my roomate had a shell basically explode out the chamber of his auto. We think the extra tight turkey choke was too much pressue, and there was blow back out the sides. We have no idea where the BBs went. I was standing behind and to the right of him, and I felt air and who knows what else blow past me. Another crazy one was when my other friend shooting an 870 basically pumped it too fast, and was in the middle of pulling the trigger while pumping, same result as previous story. That one was not as scary I believe, as it was for sure just air escaping, while the first one with the auto we have no idea what happened, the shell was in a million pieces.