I have never seen anything about how rain effects long range trajectory. Water is six times as dense as air and I would assume that a subsonic bullet might contact the water droplets and might imagine the shock wave from a supersonic bullet, as long as it is supersonic, would push the droplet away. Does anyone have any info on this. Thanks ahead of time.

In my Beloved Corps, they told us it made no consequence.

I don't know about long range but I can tell you about one range trip I had a year or so ago.

  I was shooting one of my most accurate rifles and loads at 100 yards.  The load is a .243 with a 105 grain AMAX going 2950 fps.

I just completed a ten shot group of 1/2 inch at 100 yards and was letting the rifle cool down.  It then started to rain and I mean a torrential Florida rain like 3 inches per hour.

I sat there  and waited for it to stop and it didn't.  I  decided what the hell I would shoot a few more for the hell of it and see what happens.  Well they were all in the same big hole. It may have made the 1/2 inch hole into 3/4 of an inch or so but I was amazed that the rain had seemingly no effect on the bullet at 100 yards.  I wonder how it is at like 500 yards? But anyway that one day with that load it had no effect at all.

i had a similar experience at 600 yds with a 223... i was pleasantly suprised.

Yup, I could not believe it but its true.   Just goes to show that we all have more to learn about precision shooting.

just stop and think for a minute about how much rain is actually in the air.     a heavy rain would be 1" of rain per hour.  terminal velocity on a raindrop is going to be between 10-20 mph depending on size.  converting units, that means a raindrop is traveling, 1.267 million inches per hour.   another way to say that is that it takes 1 / 352 of a second to travel one inch.   so if you took every drop that crosses your bullet's path for the entire hour, it would pass in a tiny fraction of a second.   there are 3600 seconds in an hour.  so you can see the odds of your bullet actually impacting a rain drop in a heavy downpour are actually extremely small.

math and precision shooting go together like muppets and fisting

practical effects of shooting in the rain are:

rain makes it easier to estimate the wind
harder to see through ocular lens (objective isn't affected quite as much)
causes a lot of popped primers due to overpressure from wet ammo
harder to use databooks and PDAs

you can pretty much ignore the changes to ballistics other than associated humidity/DA changes

I love seeing an occasional flash of gold in the giant turd pond.

so how many drops of rain are in an inch of rain / hour? i think your math may be missing a key piece.

i assume it doesn't matter.  it could be more small drops or fewer large drops but in aggregate, there is 1" vertically of them.    putting them all together wouldn't change the odds. (for sake of simplicity, assume a half inch raindrop and half inch bullet path gives an inch of travel.  anything smaller than that will change the odds in your favor, but no practical difference.) I think the only thing that would change the odds is the distance to the target.  but even at 1000 yards, it's highly, highly unlikely your bullet will hit a drop of rain.   if i'm wrong, which i often am, feel free to correct.

I've shot a lot of long range matches in the rain, I've never noticed a difference.  If the rain got really heavy you couldn't see the targets at distance so I couldn't tell you what bullets do in a monsoon.  

i wouldnt think it would matter, especially at shorter ranges.  the heat generated from the friction of the bullet going through the air would cause any water to evaporate before it could affect the trajectory.

i have personally seen bullets hit large rain drops mid flight, around 50y or so, this was with a 22lr look like white "poofs" about the size of a soft ball mid air..

that said, i have been shooting competition since 1981 i think, and those 2, are the only time i've ever seen that happen

Rain never actually touches the bullet itself.   There is a supersonic shock wave around the bullet, and the raindrops are displaced by that.   This is why it has no effect on trajectory.  

--Fargo007

ding ding ding We have a winner!

shock waves aren't magic and while they do affect rain drops, there are a number of variables including the speed of the projectile, the size of the drop, etc.  in essence, it takes time for the shockwave to displace it.   as there were problems with supersonic airplanes and missiles, this was studied.  there is some interesting reading on the topic in a pdf file here

An old saying.  "Rain affects the shooter, not the bullet."

The only time rain is going to affect the projectile in flight (by affect I mean alter it's flight path) is if the projectile is below supersonic speeds.  At supersonic speeds the effects of supersonic flight create a boundary layer around the surface of the bullet.  No rain will come in contact with the projectile.  However, if/when the projectile slows to the point of transonic and subsonic flight there will be no boundary layer, thus exposing the surface of the projectile to the rain.  

All things considered, if you can definitively state that a drop (or several drops) of rain altered the point of impact of your projectile while shooting at extreme long range in subsonic flight zones I want to hear about it.

My experience is that rain has not affected flight performance or trajectory.

I was shooting a custom 6.5x284 AR10 off an artillery observation tower in a coalition partner host nation back in 2008.  It was torrential downpour with heavy wind, to the point that you could see the rain going at least at a 45 * angle and higher.

I used the normal data the shooter had for his rifle (he was using Lapua radar data modeling, not theoretical drag models), and I had no problem hitting a radio-controlled reactive silhouette at well past 1100m in those conditions.  Even the tower was blowing in the wind.

In terms of trajectory and concerns over rain in the conditions, I basically ignore it as a factor for long-range shooting (other than being able to see the wind better).