Can Guns Shoot Underwater?

Have you ever watched a spy movie and wondered just how realistic it is for the hero or villain to be shooting at someone…underwater? Is it even possible: can guns shoot underwater? The answer may surprise you…

Can guns shoot underwater? Yes, many guns can shoot underwater. This includes both standard pistols and rifles and specially made underwater weapons.

The short answer to the question is, yes, guns can shoot underwater. B-U-T….should you try it???

The Science

So we know that it’s possible for guns to shoot underwater, but it’s a completely different experience than shooting on land.

I’ll explain.

On land, a bullet can travel for miles, but underwater, a bullet will likely only travel a few feet.

Why?

Well, the simple explanation is that water is much more dense than air – 800 times more dense to be exact.

While the gun will fire underwater exactly the same as it would on land, the physics are much different. Under the water, the bullet meets a lot more resistance than it would against air.

The bullet is forced out of the gun with a high amount of pressure, but that pressure changes once it hits the water. This causes the bullet to slow down drastically and eventually sink after only having traveled a few feet.

Underwater Weapons

There are weapons specially designed to be fired underwater. These weapons fire a special type of ammunition called “flechettes”, which are spear-like bolts instead of average bullets. During the Cold War era, underwater firearms were developed and used by “frogmen”, also known as combat divers.

If you were to compare the barrel of a typical firearm and an underwater firearm, you’ll find that the barrels are different. The barrel of your average firearm will be rifled.

Rifling is essentially a grooved surface inside of the barrel that helps stabilize the bullet and aid in accuracy. However, flechettes are hydrodynamic enough that they maintain their accuracy without the aid of rifling. Therefore, you’ll find that most barrels of underwater firearms are not rifled.

It is possible to shoot these weapons out of the water as well, but they lack accuracy. I will also note that underwater rifles are generally more powerful than an underwater pistol, but you’ll find that an underwater pistol is easier to maneuver. You’ll also find that an underwater firearm will have a longer range when it comes to aiming at underwater targets.

Military use

There are underwater guns specifically designed for military use. In 1974 Heckler & Koch (H&K) developed the P11 for the Navy.

This firearm had five barrels and was capable of firing 4-inch long steel darts. This weapon proved to be very effective for combat divers, as the accuracy range was up to 50 feet, depending on the depth of the water.

These weapons were multifunctional because they could also be fired on land and retain their accuracy up to nearly 100 feet.

An interesting twist is that the five barrels of the P11 arrived sealed and the rounds were basically tiny rocket propelled missiles. Instead of using gunpowder to ignite the rounds, an internal battery would be activated when the user pulled the trigger.

The battery would then send a current, ignite the fuel and the round would be launched. The only downfall to the weapon was the need to return it to the manufacturer once all the rounds had been spent in order to have it reloaded.

Can Guns Shoot Underwater: what’s the “Official” answer?

The short answer to the question is, yes, guns can be fired underwater.

Should you try it?

Unless you’re a Navy SEAL, probably not.

Guns are full of nooks and crannies and water and debris can really compromise the functionality. Remember, once your gun is submerged, water will immediately fill the barrel and anywhere else there may be an opening. 

While most modern ammunition is water tight, you still run the risk of having problems with your ammunition because the gunpowder may get wet, which in turn will cause problems with igniting.

Submerging a firearm may also compromise the action of most semi-automatic weapons. Water may cause an issue with correctly ejecting the used casing.

There are some exceptions.

In theory, a revolver should actually be more reliable than a semi-automatic firearm when used underwater. The reason being the simplicity of their design. Technically, they should still function the same underwater, but will still face the same issues with water pressure and accuracy and velocity.

Other Underwater Gun problems you may encounter

It’s important to be aware of all the things that could go wrong if you decided to fire a gun underwater. You’ll find that gas-operated rifles are more likely to function properly underwater and have fewer issues.

The most common issue you’ll run into with handguns is that they will jam due to the previously mentioned issue with ejecting the spent casing.

You never, ever want to attempt to shoot a shotgun underwater. There is very high likelihood that the barrel will explode and destroy the gun and injure you or someone around you. Do NOT try this. Just don’t do it.

You should also remember that once your firearm has been removed from the water and you want to attempt to shoot it on dry land again, it will need to be thoroughly inspected.

Any water remaining in the firearm must be dried completely. In some weapons, water will lead to rust, which leads to a non-functioning firearm. Be sure to check the specifics for your firearm. You’ll definitely want to know exactly what type of frame it has and if any of the parts are made from metal.