What happened to it?

Try to clean it up a bit, acid, naval jelly, whatever. Look to see if there's a damascus pattern. Some very old shotgun barrels were made by twisting a ribbon of steel around a mandrel and welding it together to form a tube. OK for low pressure black powder, but a high pressure smokeless load could rupture the barrel.

I agree with Roy that it may be the result of a plugged barrel. Did you find any teeth or bits of skull in the vicinty? 8*)

Cheers! Red

Huh, it does kind of look as if the ribbon has "unwound", the way it's twisted like that. Each barrel is unwinding in the opposite direction. Imagine that when it blew, the muzzle end went north and the breech end south, leaving the guy with a part in each hand, going like a pinwheel.

I'll put it in the electrolytic bath; don't know why I didn't think of it. But it's pretty far gone, as far as pitting.

I should have looked around for other parts (shotgun parts, not body parts). But I was too excited with the great find. As a kid, this was about tops as far as cool found objects go.

I believe it was Elmer Fudd's ... I recall Daffy sticking his fingers down the barrel just as Elmer pulled the trigger.