How do bullets behave in the rain?

I’ve heard a fair bit of conjecture over the years about what happens when a bullet flies through the rain. Speculation varies from nothing to maybe something. Until now, all I’ve had is an opinion. After conducting tests at EMRTC (New Mexico Tech) (emrtc.nmt.edu) for Guns & Ammo TV, observed by a team of ballisticians, I can honestly answer, “A lot more than you think.”

The most common speculation I’ve heard is that a pressure wave forms on the supersonic bullet’s nose and pushes anything out of the way — and water never touches the bullet. I’ve also heard that even if water hits the bullet, it moves too fast and has enough mass that a drop has no effect. Both hypotheses are false.

The impetus for this test was Dave Emary who write’s this magazine’s “Bullet Board” column. Emary shared with me an experience he had shooting a High Power Match at Camp Perry, Ohio, during which some serious rain showed up. Dave was shooting and doing just fine until he had one bullet barely clip the edge of the entire 600-­yard target board. It wasn’t just a few inches away from the rest of his group — it was a few feet! Dave was shooting an M1A chambered in .308 Winchester using 180-­grain bullets when his bullet hit about 3 feet away from his expected impact.

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… EMRTC had the instrumentation to film a bullet hitting a drop of rain, so we decided it was time to find out exactly what happens when a bullet hits a drop by filming it occur in high speed.

Engineer David Hibbert and a couple of PhD candidates determined that a drop of rain induced a 3.2-­degree yaw on our 125-­grain bullet. Thanks to some judicious pixel counting by our big-­brained team of scientists, we also determined that the bullet’s yaw was not directly correlated to the flight path; 3.2 degrees is some serious yaw. We observed 4 inches of deflection at 50 yards, however, the bullet could have hit multiple water droplets due to our test setup.

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Does this mean that shooters need to worry about shooting in the rain? No. Even in a pretty steady rain, the likelihood of hitting a drop with a bullet is pretty low. However, there are a couple of instances where it would be worth remembering this study, should you find yourself shooting in wet weather.

Via Woodpile Report.  This is an interesting result, but not one I would try to plan or train for.  On a related note, I recall one time that “Myth Busters” tested the notion that walking faster or running in the rain caused you to get less wet than if you walked slowly.

It’s not true.  You can see rain drops in terms of specific concentration, or drops per cubic foot or cubic meter (or your favorite volume dimension).  You’re going to walk through the same number of water droplets running as you will walking.

For those who care.