Will A Gun Fire Underwater?

I get this question once in a while from authors and when I saw this video I figured now was a good time to address it again. This video is interesting for a couple of reasons.First and foremost it dispels the rumor that guns won't work underwater. This is not a new finding. Despite comments from the videographer, this question has been addressed by researchers and professional (military/police) for a long time.

Now, water can dramatically affect both the velocity and flight path of a bullet. In fact, many police crime labs use water tanks to fire test bullets into. The water stops the bullet in a relatively short distance and doesn't leave any markings (rifling) on the bullet which may complicate the comparison to a bullet recovered from a crime scene. What this means for authors is that your gun will only be lethal for perhaps a few feet (depending on caliber). Even if the bullet retained enough velocity it would likely veer off it's flight path towards the target. So when your hero is diving under the water and is ten feet down; he's probably pretty safe from the bad guys firing into the water from the boat above; especially if they are just firing handguns.

Another interesting observation in the video is that of the gases expelled from each gun. The video gives the viewer an insight into how these gases are expelled. With the revolver there are two basic "areas". One is between the barrel and cylinder. This is often referred to as a "cylinder gap". CSIs sometimes see these on walls or door frames where a person barricaded themselves while shooting. It is clear evidence that a revolver was used. In contrast, the semi-auto pistol expelled most of the gases out of the muzzle. These gases are important in forensics because they also contain and propel gunshot residue which can land on the suspect.


Guns are metal so prolonged exposure underwater can have detrimental effects on the working parts. But brief exposure shouldn't cause too many problems in the short term. Some guns like the Glock were originally designed for military Special Forces and have small grooves in the frame that allows water to flow out of the gun after it is brought out of the water. Contrary to the video host, some guns have been designed with submersion in mind. So don't be afraid to get your fictional guns a little wet, as long as it isn't for days on end.