Everybody that shoots shotgun will do it sooner or later. Fortunatly, mine was when I was 6 and was using a 410 as a walking stick and fired it off. Boy, was that ugly.

You can cut it down to 18.5" and try to sell on ebay as a home defense barrel. I bet you can get a buyer. Just be honest with what happened. A fella should be able to few down the barrel and see any visible bulges or push a tight cleaning rod with patches down and feel for any place in the barrelwhere there is a bulge. If it only happened at the tip, I doubt there is any problems near the breech. If the object that was in the barrel real deep, it would have probably blown a hole in the side of the barrel.