How deep does a .45 ACP penetrate Water?

At the muzzle, a representative .45 ACP load penetrates approximately 3113 mm (122.6 inches) into water.

What is the impact energy of a .45 ACP?

This .45 ACP load carries about 504 joules (371 ft-lb) at the muzzle.

Penetrates to ~123″ before stopping

Penetration depth

3113 mm (122.6″)

Impact velocity

260 m/s (853 fps)

Muzzle energy

504 J (371 ft-lb)

Bullet behaviour

Intact

Fired at the muzzle, a representative .45 ACP load (14.9 g, FMJ, 260 m/s) reaches roughly 3113 mm (122.6 inches) into water.

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