How far can bullets travel when fired into water?
 

http://www.straightdope.com/mailbag/mgununderwater.htm

Dear Straight Dope:

When a bullet is fired from land into water how far can it travel? Movies portray a long trajectory, but I remember reading an Ian Fleming book many years ago where he described that a bullet travels a yard at most before it loses its speed and thereafter just slowly sinks. Given that some bullets are more aerodynamic (hydrodynamic?) and some can have greater speeds, how far can a bullet travel when fired into water? �A. A.

SDStaff Bricker responds:

It�s almost a shame that Cecil chose to assign this project to the SDSAB; it strikes me as a fine candidate for the sort of hands-on experimentation for which the Straight Dope is famous. However, you can see where letting Little Ed near live ammunition might not be entirely wise.

Besides, somebody beat us to it, namely the daredevils on "Mythbusters," who have a bigger budget anyway. In an episode airing July 13, 2005 on the Discovery Channel, the M-busters team built a water tank with thick acrylic sides braced with iron T-bars. Ballistics gel � in place of human flesh, thank goodness � was placed in the tank at various depths to simulate the terrified swimmer escaping a bloodthirsty assassin. The team collected a doomsday arsenal consisting of a 9mm semi-automatic pistol, an M1 Garand, a hunting rifle chambered for .223 ammunition, a shotgun, a .50 caliber "armor piercing" rifle, and, for fun, a replica Civil War-era black powder rifle.

In their first experiment, the experimenters shot the 9mm pistol straight down into the water. At a range of up to seven feet, the 9mm round was effective in completely penetrating the ballistics gel � meaning a person at the same range would be killed. At eight feet, the bullet entered but did not exit the gel, indicating a possible non-fatal wound. Past eight feet, the gel was undisturbed.

The shotgun, loaded with a 3� deer slug instead of buckshot, not only "killed" the ballistic gel target at six feet, it destroyed the acrylic water tank, ending that method of testing.

The team then switched to a swimming pool to continue the experiments � and to make the test more realistic, switched from shooting straight down to an angle of twenty to thirty degrees off the vertical, approximating a shooter standing on the edge of the water and shooting out into it.

The first candidate for this test was the Civil War rifle. At a range of 15 feet, the ballistics gel was completely unharmed; likewise at five feet. Only when the range was reduced to three feet did the bullet finally penetrate the gel, suggesting that diving under water was probably a pretty effective way of dodging slugs during the Civil War.

The experimenters moved on to the hunting rifle, which was loaded with a full-metal jacket .223 round that emerged at roughly 2,500 feet per second. At ten feet, the bullet disintegrated and the gel was untouched. At three feet, the bullet again broke up, with its tip coming to rest on the gel � not nearly enough power to damage flesh.

A bullet from the M1 Garand, with a muzzle speed of 2,800 ft/sec, also disintegrated at the ten-foot range. At two feet, the slug penetrated about four inches into the gel, suggesting a non-fatal wound. The armor-piercing .50 caliber round didn�t do any better � it, too, came apart at distances greater than five feet and lost most of its punch by three feet.

The Mythbusters team concluded that you�d be safe from firearms even if they were fired straight down to a depth of eight feet, and probably safe at much lesser depths, especially if the bullet was aimed at an angle.

But that�s not the whole story, although it's the most dramatic part. In our ingenious age, for almost any imaginable environment, chances are there's somebody who's figured out a way to shoot guns in it. It's even so with shooting into (or under) water.

The problem that the Mythbusters faced was mostly due to the shape of the bullets � what works well in air isn't an advantage underwater. Rifling of a barrel, which cause the bullet to spin and provides aerodynamic stability, is useless in a water environment.

The engineers at the Central Scientific Research Institute for Precision Machinery Construction in Moscow correctly perceived the problem with shooting into water and in response developed the SPP-1 (Spetsialnyj Podvodnyj Pistolet, or �Special Underwater Pistol�) for use by Russian Navy frogmen. The SPP-1 is a manually operated four-barrel handgun that breaks open along the top and loads in a fashion similar to a double-barrel or over-and-under shotgun. The ammunition is designed to work underwater, using long bottlenecked rimmed casings plus bullets made from mild rather than hardened steel and designed to be stable underwater. The barrel isn't rifled. According to the specs for the pistol, when fired at a depth of five meters � over sixteen feet � it's lethal up to seventeen meters, or over fifty-five feet.

The SPP-1 isn't the only exemplar of the breed. Other firearms are designed to work underwater as well, but they tend more towards the spear-gun model using dart-like projectiles. There�s no bright-line boundary where a bullet becomes a dart, but the projectiles fired by the Heckler & Koch P11 Underwater Pistol, for example, clearly cross the line. The H&K is an all-polymer weapon made especially for underwater use by the German Bundeswehr Kampfschwimmer � �army combat divers.� Each of the five dart-shaped projectiles is powered by a small, solid-fuel rocket. The weapon has been featured in some high-profile films, including Tomb Raider with Angelina Jolie, and is said to be able to inflict a fatal wound at fifty feet underwater.

So the general rule is that most ordinary guns and bullets aren't tremendously effective when fired into the water, and if you can dive below eight feet, you�re probably safe from your run-of-the mill assassins. But if you�ve incurred the wrath of the Bundeswehr, all bets are off. You may as well stay dry and meet your fate like a man.

Sources

http://www.gizmowatch.com/entry/spp-...rwater-pistol/

http://www.securityarms.com/20010315.../2100/2153.htm

http://www.securityarms.com/20010315...s/0900/940.htm

http://kwc.org/mythbusters/2005/07/m...oof_water.html

�SDSTAFF Bricker
Straight Dope Science Advisory Board

Re: How far can bullets travel when fired into water?
 

I saw that Mythbusters episode.

Surprising that the lower velocity ammo (pistol) would travel farther. The high velocity ammo literally disintegrated right after entering the water.

Maybe you could make body armor from large jugs of water!

Re: How far can bullets travel when fired into water?
 

You need jugs a few feet in diameter

try this site to see how jugs do.

http://www.theboxotruth.com/

Re: How far can bullets travel when fired into water?
 

Im sorry but who would really care how far a bullet would travel in water, this guy really needs a life. Its like how many feathers are in a pound?

Re: How far can bullets travel when fired into water?
 

I didn't know infidels liked to swim?

Re: How far can bullets travel when fired into water?
 

This is because the surface tension of the water acts basically as concrete at high velocities. That's why people rarely survive jumping from the Golden Gate bridge (as an example). By the time they hit the water, they are traveling fast enough that it is basically simulating jumping onto a parking lot from 100+ feet in the air.

At lower speeds (or if the water is frothy), the penetration is greater because the surface tension has a lesser effect (or is disturbed).

Re: How far can bullets travel when fired into water?
 

I have a solution to this then. have the SF golden gate overseers install large buckets of liquid soap that are automatically flung at high speed at water close to where the jumper would enter water

oh

and the bill should be footed by the jumpers.

Re: How far can bullets travel when fired into water?
 

Unless you're wearing SCUBA gear... Ya got to come up for air sometime.

Re: How far can bullets travel when fired into water?
 

Or, just let them jump. It's not like their hurting anyone else.

Re: How far can bullets travel when fired into water?
 

all the way to the bottom. :tongue:

Re: How far can bullets travel when fired into water?
 

Man....Gold Rocks....you beat me to the obvious answer !!! That's what jumped out at me as soon as I saw the thread header....ahahahahaaaa

Re: How far can bullets travel when fired into water?
 

Remember the physics questions where they would fire a rocket and give you certain info and then have you calculate how far it would go or what its initial velocity would be?

I was in a two year technical program and had to take a physics class. One of the questions on the final had the rocket launcher on the bottom of the ocean. Needless to say grades were low on that test.

Re: How far can bullets travel when fired into water?