| M1 Underwater Defense Gun | |
|---|---|
| Type | Underwater pistol |
| Place of origin | United States |
| Service history | |
| In service | 1970–1976 |
| Wars | Falklands War[citation needed] |
| Production history | |
| Designed | 1967 |
| Specifications | |
| Mass | Empty: 2.26 lb (1.03 kg) Loaded: 4.17 lb (1.89 kg) |
| Length | 9.75 in (248 mm) |
| Barrel length | 4.25 in (108 mm) |
| Cartridge | Mark 59 Mod 0 Projectile |
| Barrels | 6 |
| Action | Double action only Pepper-box |
| Rate of fire | 12 rpm |
| Muzzle velocity | 740 ft/s (230 m/s) |
| Effective firing range | 30 ft (9.1 m) |
| Feed system | 6-round removable cylinder |
The M1 Underwater Defense Gun, also called the Underwater Defense Gun Mark 1 Mod 0, is an underwater firearm developed by the United States during the Cold War. Similar to other underwater firearms, it fires a special 4.25-inch (108 mm) metal dart as its projectile.