So basically as the title states, Can I take a shotgun that has a smooth bore and no threading for chokes, and have it threaded so I can add a door breacher? specifically, to this gun. Pump Action Shotgun - Model 870 Marine Magnum - Remington Shotguns No, It's not for a practical purpose. It's strictly for Bada$$ery . Can this be done, and if so, how common is it, and what is the approximate cost?