Safety and Training

Is Your Gun Waterproof?

waterproof gun in action

The expression “all skill is in vain when an angel pees in the touch hole of your musket” reflects the inability for guns to function reliably in the rain. This expression was popular up until the 1830s percussion caps.

Fifty years later, cloth machine gun belts would fail when wet, and all the way up to the late 1940s, scopes would fog up from temperature changes.

Today, many guns have become more water-resistant. But just because your gun is modern doesn’t mean it’s waterproof.

So, how well does your gun fare in the rain? Can it survive a dunking should you have to take cover in a water-filled ditch or stumble when crossing a stream?

These are questions to ask yourself when determining whether your gun is waterproof or not.

rain waterproof rifle

Types of Gun-Related Water Problems

The problems posed by rain or standing water range from long-term rust and failure to function to catastrophic blowup on firing. Let’s take a look at three of the most common.

#1: Rust

The first issue may be mitigated with the use of stainless and chemically coated components and plastics, but is only solved with careful maintenance.

Every time a weapon is exposed to condensation, rain or immersion, it should be stripped and dried with water-displacing chemicals, towels and dry air.

#2: Failure to Function

A more immediate problem is the failure to function—due to water collecting in the firing pin channel or interfering with feeding. Clean moisture is one thing, but standing water often deposits grit or silt into the weapon, greatly increasing friction between parts.

The only way to get around this is to prevent immersion or to mitigate the influx of dirt with a plastic or oilcloth wrap. In testing, well-sealed weapons like K98, M16 and G3 have fared much better than the more open designs of the M1 and the M14 type.

Perhaps the most dangerous effect of waterlogging is the capillary action holding water in smaller caliber barrels, such as 5. 56mm.

A bolt-action hunting rifle barrel may well burst if a high-velocity bullet hits incompressible liquid. Opening the bolt and shaking the rifle usually dislodges the water, enabling a safe shot.

#3: Sight Failure

Of separate concern is the failure of sights. Small aperture sights have the same capillary action problem as the small bore barrels. Open sights seldom get waterlogged, and neither do ghost rings.

Most higher-end and mid-grade scopes are entirely waterproof, though they may well rust over time. The same is true of red dot sights, lights and lasers.

The trend towards ergonomically poor membrane buttons has come mainly from the effort to make waterproof devices on a limited budget.

rifle in action

Waterproof Isn’t Fool-Proof

For fair-weather shooting, this is all of minor importance. For use at the dire extremes, or under extreme conditions on a hunt, it would be useful to know just how much your weapon system can take.

With MIL-SPEC guns and accessories, test information is usually publicly available. Unofficial tests are usually available for any sufficiently widespread optic or weapon. Water-resistance is one of the factors separating a $30 “airsoft special” from a $300 optic.

The same waterproofing gaskets also serve to keep out dust, which is an equally potent destroyer of optics.

Keep in mind that, despite internal waterproofing and nitrogen fill, condensation on the outside of objectives can still happen, including frost from the shooter’s careless exhalation in winter. A backup mechanical sight might just save the day in that case.

Is your gun waterproof? Do you have experiences with waterlogged guns? Let us know in the comments below.

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

1 Comment;

  1. Well my SIG Romeo 5 is listed as waterproof to one meter…not exactly what I was hoping for but it’ll do. I always like BUIS, even though the MagPul MBUS I have are plastic, not metal like the Pro. Nice to see the AR design is better at water resistant than some, and I was taught the “retract the bolt slightly after crossing the river to break the seal and let the water drain out” move back in ROTC.
    Interesting article and something people don’t think about, especially if out in the woods long term.

Your email address will not be published. Required fields are marked *

Time limit exceeded. Please click the reload button and complete the captcha once again.

Your discussions, feedback and comments are welcome here as long as they are relevant and insightful. Please be respectful of others. We reserve the right to edit as appropriate, delete profane, harassing, abusive and spam comments or posts, and block repeat offenders. All comments are held for moderation and will appear after approval.