Some years ago, a shooter from a country in which reloading supplies were unavailable and/or prohibited posted his method for firing 2 3/4" shells in a 16-gauge short-chambered Browning auto. As you probably know, such a gun will fire a 2 3/4" shell but the ejection port is too short for proper ejection. He put the unfired factory shell in a drill press and used a small hole saw to make a circular weak spot in the end of the cartridge. Upon firing, the plastic circle went downrange like an overshot wad and the shortened empty ejected cleanly.
