spp-1
The SPP-1 (СПП, Специальный Пистолет Подводный "Special Underwater Pistol") A Soviet double-action handgun designed in late 1960s, intended for frogmen use. It fires 4.5×40mmR cartridge that has a 115 mm long steel dart. The weapon has four smoothbore barrel that is hinged to the frame, and a huge rounded trigger guard. Reloading is similar to any break-action firearm, with a clip.
SPP-1M is the improved variant.