I was recently told that you can make a 12g shotshell from a .50BMG casing. They said to peen the front of the rim to thin it out to about the right thickness, then file it to the correct diameter. Also, cut the case off about a quarter inch behind the neck. Prime, load the powder charge, use felt wads like in a muzzle loading shotty, load the shot or whatever projectile you're using, and fill the end with parafin wax. Seems to be workable, case head's the right size, but I don't have the brass to try it. Has anyone else here tried this? By the way, yes, I do realize this is almost completely pointless, due to cost, but it has one heck of a curiosity factor.