Use the Gun Gauge Adapter Insert set with any SAAMI spec break-open 12GA shotgun to shoot the most popular centerfire pistol cartridges. Includes 8 Inserts: 380ACP, 9MM, 357MAG/38SPL, 40S&W, 44MAG, 45ACP, .410/45COLT, 20GA (All Rifled Except 20GA)