Does Rain Affect Bullet Trajectory?

[robert hode]

If wind -- a compressible gas -- can move a bullet in flight; can rain, a non-compressible liquid do the same?
I'm talking about enough to make actual adjustments on the scope.

[rksimple]

Theoretically yes. In the times I've shot in the rain, its only been to 600 yards or so, and I saw no noticeable difference in dope.

[AR15barrels]

I have not noticed a problem with centerfires, but with rimfires, you will get occaisional random fliers that go 2-4 moa LOW which tells me that those are the bullets that hit raindrops.

[Connor P Price]

I have not noticed a problem with centerfires, but with rimfires, you will get occaisional random fliers that go 2-4 moa LOW which tells me that those are the bullets that hit raindrops.

I've seen the same thing shooting my 22 in the rain, vertical spreads like you would not believe at 50 yards.

When its raining out the air is full of moisture as well so it should be denser. I would guess that should create more drop right? I have never shot my bolt gun in the rain though.

[MercilessMike]

Just a thought on the subject:
With a centerfire round, we are talking speeds at muzzle of 2500 - 3000 fps. The shockwave produced in that dense air may actually "push" a raindrop away, as a matter of inertia. Wind in always pushing on the round thus pushing the round and the shockwave evenly at any given moment. Now with a stronger down pour, visibility would suffer thus a clean shot couldn't be made.

With a rimfire, much smaller bullet at a much slower speed. So with my thoughts on this, a rimfire in a misty drizzle would be the same as a .308 in a light rain.

Anyone care to put this idea to the test?

[DirtRacer151]

Just a thought on the subject:
With a centerfire round, we are talking speeds at muzzle of 2500 - 3000 fps. The shockwave produced in that dense air may actually "push" a raindrop away, as a matter of inertia. Wind in always pushing on the round thus pushing the round and the shockwave evenly at any given moment. Now with a stronger down pour, visibility would suffer thus a clean shot couldn't be made.

With a rimfire, much smaller bullet at a much slower speed. So with my thoughts on this, a rimfire in a misty drizzle would be the same as a .308 in a light rain.

Anyone care to put this idea to the test?

pretty sure we would have to move to Seattle to do that!

I've always heard it explained just as you described it. It makes sense to me.

[buffybuster]

Just a thought on the subject:
With a centerfire round, we are talking speeds at muzzle of 2500 - 3000 fps. The shockwave produced in that dense air may actually "push" a raindrop away, as a matter of inertia. Wind in always pushing on the round thus pushing the round and the shockwave evenly at any given moment. Now with a stronger down pour, visibility would suffer thus a clean shot couldn't be made.

With a rimfire, much smaller bullet at a much slower speed. So with my thoughts on this, a rimfire in a misty drizzle would be the same as a .308 in a light rain.

Anyone care to put this idea to the test?

I was giving this some thought. This is what I came up with as a WAG regarding supersonic bullets:

1. No matter how hard the rain is, as the percentage of the total volume of air in a given bullet flight tunnel, the rain is a very small percentage (compared to air). So on that, the odds of a bullet actually hitting a raindrop dead on is very, very slight with odds increasing as ranges increase due to greater volume of air traveled through and longer time of flight.

2. A supersonic projectile has a shockwave that propagates from the tip (but not touching). That is the air that is compressed, unable to move away from the projectile, until a shockwave is formed. This shockwave is very thin but hard and hot. If the projectile were to hit a raindrop dead on, the raindrop has a much lower mass than the bullet and impacting the shockwave there probably would be instantaneous boundary layer created which would push the remainder of the rain drop away.

3. The projectile is spin stablized at approximately 3000 Revolutions per Sec, if a rain drop would hit dead on, the force would alter the vector of the bullet tip but I think it would be so small, as compared to the total stabilizing force that it would not make noticeable difference to Mid-Range. Also, when the raindrop is hit would make a greater difference. If the raindrop was hit at the muzzle the change would be greater than 50yds from the target (though the stabilizing force of the bullet would be higher at the muzzle than at the target).

So, I don't think rain would make much difference out to 600yds.......... Beyond that, the rain might become a larger influence, but then so does wind and everything else. Rain might just become swallowed up in all the background noise. Like to test it under controlled conditions. Something else to do when I go to heaven......

In subsonic flight, I think only 1 and 3 would apply, since there is no shockwave. Also depending on the rifling twist, there may not be so much stabilizing force. The Time of Flight would also be increased, increasing the chance of hitting a raindrop.

[MichaelV]

I've been told by working mil snipers that rain has no affect on bullet flight. No sure how that is possible but I've heard it from a pro.

[buffybuster]

I've been told by working mil snipers that rain has no affect on bullet flight. No sure how that is possible but I've heard it from a pro.

That conclusion is from empirical observation. But why this is so is the question, to my mind.

[AR15barrels]

Anyone care to put this idea to the test?

I don't like shooting in the rain.
You get wet.

[MichaelV]

I don't like shooting in the rain.
You get wet.

Can only be tested the three days a year it rains in the southland.

[Fjold]

I was giving this some thought. This is what I came up with as a WAG regarding supersonic bullets:

1. No matter how hard the rain is, as the percentage of the total volume of air in a given bullet flight tunnel, the rain is a very small percentage (compared to air). So on that, the odds of a bullet actually hitting a raindrop dead on is very, very slight with odds increasing as ranges increase due to greater volume of air traveled through and longer time of flight.

2. A supersonic projectile has a shockwave that propagates from the tip (but not touching). That is the air that is compressed, unable to move away from the projectile, until a shockwave is formed. This shockwave is very thin but hard and hot. If the projectile were to hit a raindrop dead on, the raindrop has a much lower mass than the bullet and impacting the shockwave there probably would be instantaneous boundary layer created which would push the remainder of the rain drop away.

3. The projectile is spin stablized at approximately 3000 Revolutions per Sec, if a rain drop would hit dead on, the force would alter the vector of the bullet tip but I think it would be so small, as compared to the total stabilizing force that it would not make noticeable difference to Mid-Range. Also, when the raindrop is hit would make a greater difference. If the raindrop was hit at the muzzle the change would be greater than 50yds from the target (though the stabilizing force of the bullet would be higher at the muzzle than at the target).

So, I don't think rain would make much difference out to 600yds.......... Beyond that, the rain might become a larger influence, but then so does wind and everything else. Rain might just become swallowed up in all the background noise. Like to test it under controlled conditions. Something else to do when I go to heaven......

In subsonic flight, I think only 1 and 3 would apply, since there is no shockwave. Also depending on the rifling twist, there may not be so much stabilizing force. The Time of Flight would also be increased, increasing the chance of hitting a raindrop.

I agree with everything except that a bullet at 3,000 ft/sec out of a 10" twist barrel will be spinning at 216,000 RPM

3000'/sec * 60 sec/1 min * 12"/1 Foot * 1 rev/10" = 216,000 RPM

[aimsmallmisssmall]

The only water I worry about is the water in my knees. Oh, water goes well with Scotch

[buffybuster]

I agree with everything except that a bullet at 3,000 ft/sec out of a 10" twist barrel will be spinning at 216,000 RPM

3000'/sec * 60 sec/1 min * 12"/1 Foot * 1 rev/10" = 216,000 RPM

3000fps from 1:10 twist = 216,000RPM = 3600RPS (Revolutions per Second)
3000fps from 1:12 twist = 180,000RPM = 3000RPS

I was using 1:12 twist because it was easier.

[Fjold]

3000fps from 1:10 twist = 216,000RPM = 3600RPS (Revolutions per Second)
3000fps from 1:12 twist = 180,000RPM = 3000RPS

I was using 1:12 twist because it was easier.

Reading is fundamental, I should learn to do it.

[buffybuster]

Reading is fundamental, I should learn to do it.

Does this have anything to do with your difficulty in differentiating East from West...................

[AR15barrels]

Does this have anything to do with your difficulty in differentiating East from West...................

I'm pretty sure it does.

[Gnzrme]

Does this have anything to do with your difficulty in differentiating East from West...................

you are never going to let him live that down are you? ....Hey guys, you should see Frank now....He must be out doing something (like learning to read maps/compasses), because he has lost a ton of weight since I last saw him...He ended up showing up at Cuyama and I didn't recognize him.....Good Job Frank!!!