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Does Rain Lower Your Bullet's Point of Impact?

Does shooting in the rain result in a lower point of impact? The BullShooters investigate.

The Myth
Shooting in the rain causes bullets to impact lower than normal.

The Reasoning
It's simple, right? A bullet flies horizontally, raindrops hit the bullet from above, imparting their mass on it, causing the bullet to fall faster and impact the target lower.

The Facts
Sometimes the physics are counter-intuitive.

Fact is, bullets normally impact higher than normal when it's raining, as anyone who has shot extensively in the rain knows. Why? As the NRA Fact Book states: "Changes in humidity have little effect on the air density, and thus on the flight of the bullet. Changes in barometric pressure, on the other hand, do have an effect. In general, fair weather is accompanied by a high barometer, which means more air density and more resistance to the bullet. Likewise, rainy weather is likely to occur at times of low barometer, when air pressure is low, producing less air density and resistance to the bullet. A drop of 1" in the barometric reading will increase the ballistic coefficient by about 3.33 percent."

The Answer
Shooting in the rain generally causes bullets to impact higher than normal, not lower.

And oh, what a glorious feeling ... to be shooting in the rain!

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2 Responses to Does Rain Lower Your Bullet's Point of Impact?

G. Hammer wrote:
August 25, 2014

Seems to me that a rain drop would be fallowing much slower than the speed of a bullet. So, the bullet would be impacting the drop of water, which has a mass. Depending on how heavy the rain was, the numbers of drops hit would vary. I would think that the mass of the rains drops being stuck would have some impact on the speed, thus accuracy, of the bullet. Just like a leaf or a twig would, and we sure don't like shooting though them!

george wrote:
August 07, 2014

I would think that hitting drops would make more difference than barometric pressure. Mean free path and droplet size are certainly part of the equation. I think this article is too simplistic.