How deep does a 5.56 NATO penetrate Water?

At the muzzle, a representative 5.56 NATO load penetrates approximately 991 mm (39.0 inches) into water.

What is the impact energy of a 5.56 NATO?

This 5.56 NATO load carries about 1693 joules (1249 ft-lb) at the muzzle.

Penetrates to ~39″ before stopping

Penetration depth

991 mm (39.0″)

Impact velocity

920 m/s (3018 fps)

Muzzle energy

1693 J (1249 ft-lb)

Bullet behaviour

Intact

Fired at the muzzle, a representative 5.56 NATO load (4 g, FMJ, 920 m/s) reaches roughly 991 mm (39.0 inches) into water.

Water is a dense fluid medium; bullets destabilise and shed velocity quickly.