X Caliber Rifled Shotgun Inserts allow the user to fire many different flavors of ammunition.
Just how well do these work in that old scatter gun of yours?
This shooter tests them out at the range.
Picture this scenario. You are in the heat of battle with un-dead zombie hordes and your handy, reliable shotgun is out of shells. You do have a pouch of X Caliber Rifled Shotgun Inserts and a handful of various pistol cartridges and lower gauge shotshells.