Underwater Firearm - Design

Design

Because standard ammunition does not work well underwater, a common feature of underwater firearms is that they fire steel darts instead of standard bullets.

The barrels of underwater pistols are typically not rifled. Rather, the fired projectile maintains its ballistic trajectory underwater by hydrodynamic effects. The lack of rifling renders these weapons relatively inaccurate when fired out of water. While underwater rifles are more powerful than underwater pistols and more accurate in out-of-water applications, underwater pistols can be manipulated more easily underwater.

Among the many engineering challenges in designing underwater firearms is that of developing a weapon which can be effective in both underwater and out-of-water applications. The ASM-DT amphibious rifle is an early example of such a weapon. First fielded by the Russian special forces in 2000, the folding-stock ASM-DT amphibious rifle is capable of firing two kinds of ammunition, both of 5.45 mm caliber:

1. 5.45×39mm rifle cartridge (7N6 enhanced penetration variant) for above water use; and
2. 5.45x39mm rifle cartridge (MGTS variant) for underwater use. The projectile in this case is a steel dart, 120 mm in length (the two images in the middle are of this cartridge and its associated projectile).