Rain affecting bullets

Some reports I have seen say the opposite, little or no effect even on light bullets. Now rain may be accompanied by wind and that will certainly affect bullets, but ordinary rain seems to have little effect since the actual drops are separated by both time and space.

Jim
 
I have only been called on to shoot in the rain a few times.
I found that the rain affected me a lot more than it did the bullets.
When I could ignore the rain, I got a center hit.
 
I've never seen rain cause a problem.
And most people that have studied the concept conclude that the aerodynamic shockwave will disrupt the raindrop with little to no impact on the bullet's flight.

A few years ago, I did the math for the odds of hitting a rain drop in a two-inches-per-hour rain storm.

My conclusion (assuming constant velocity):
A .308" diameter bullet traveling at 2,100 fps to a 100 yard target has just a 0.0139% (1:7175) chance of hitting a rain drop.
The smaller the bullet, the better the odds.
The faster the bullet, the better the odds.
A .224" bullet traveling at 3,900 fps has only a 0.0054% (1:18,323) chance of hitting a rain drop in a two-inches-per-hour rain storm.

And the jury is still out on whether or not the rain drop would even matter.


High humidity... I honestly don't know.
Instinct tells me that a denser atmosphere will cause more drag and slow the bullet more quickly; but ballistic calculators spit out higher velocities (and subsequently less bullet drop) with higher humidity levels.
 
Out in the real world, there's probably going to be more stuff in the way of the bullet than rain drops.
If you ever take a shot and are mystified why nothing hit the target, check to see if there's maybe a hard to see tree branch or something in the flight path.
Since we live in an area of very high summer humidity, about the only thing the humidity seems to cause is being able to sometimes actually see the bullet in flight.
Very cool.
 
Well dang, almost forgot the funny story about having things in the way of the shot.
At a rifle match with targets at an undeclared distance, one poor guy was having a heck of a time.
He keeps adjusting and readjusting his scope and getting absolutely nothing on target.
All the while the RO who is viewing everything through a very large spotting scope is chuckling away every time this fellow takes a shot.
After awhile the RO moseys over to the guy and kind of casually asks how he's doing.
After hearing all the fellow's complaints about his malfunctioning scope or crappy ammo, he takes pity on the guy and invites him to take a look through the spotting scope.
It turns out there's a good sized tree blending in so well with the background that it's practically invisible.
And it's right in the path of every shot the guy has been taking and stopping or deflecting every shot.
Tree scored 100, target scored 0.
 
The question has come up many times. Here is my answer from several years ago:

http://thefiringline.com/forums/showpost.php?p=5625689&postcount=26

There's not nearly as much water in the air during a rain storm as some folks seem to believe.

Let's just use a simple thought process as an example. It may not be perfectly scientifically, mathematically correct but it's close enough to give you an idea.

Let's say it's raining at a very heavy 5 inches per hour. This is at least 20% higher than, and more likely 2-5x higher than, an average rain fall.

To get a really good number and put everybody to sleep, we'd have to use some fun calculus (Δt → 0) and other fun stuff.

I'm going to guesstiproximate instead.

Let's go with a 180gr .308 bullet at 2,600 fps MV. That bullet (according to JBM Ballistics) would take about 1.9 seconds to get to 1,000 yards. Let's call it 2 seconds for easy math.

Let's do some simple extrapolation,

A 5"/hour rain fall literally means that it takes one hour to fill a space with 5" water. There are 3,600 seconds in an hour. The bullet is in flight to 1,000 yards for 2 seconds. During that 2 seconds, only 2/3600ths of the total 1 hour rain will fall. That means that during the entire bullet flight time, the total amount of water in the air is 5 inches x 2 divided by 3,600 seconds. That's 1/360th of an inch (~0.0027777) of rain in that time. That amount is broken up evenly throughout the entire space.

Let's consider the space taken up by the bullet. Let's make it a 1,000 yard cylinder, 0.308 inches diameter. We have a cylinder 3,000 feet (36,000 inches) long with a .308" diameter. The total volume of that cylinder is 2,682 cubic inches. An average raindrop might be about 0.078 inches in diameter. That's a volume of ~0.0019877 in3.

In that 2 second flight time, we're only filling that entire cylinder with 1/360th of an inch of rain. That's a total volume of rain within that cylinder during time of flight of 0.000206955 in3.

Look at those two numbers, total volume and rain drop volume.... there's more zeros in the total volume than there are in a single rain drop!

That means that in the entire flight of the bullet, there will be less than one rain drop in it's entire path... ahead AND behind it!

Not just "less than one", a single drop of rain is almost 10 times the total volume of water in that column during the entire bullets flight!

You tell me. There's essentially 1 drop of water SOMEWHERE in the flight path of every 10th bullet. That's in front and behind. We could sort of almost consider that it would take 20 shots to get a single drop of rain to be somewhere in front of the bullet during it's time of flight.

You wanna take the bet that you're going to hit one?
Click to expand...
 
Rain has a tremendous effect on shooting. None on the bullet.

So, calculations show that the odds of hitting a raindrop are tiny teeny small.

Odd on ran affecting your ability to see, and sight on a target are huge. ;)
 
You know it's raining too hard when your holster fills up to overflowing with water.
But heck it's still only water.
Now on the other hand, if there's a huge flock of geese flying overhead.........
 
I have hunted in steady downpours but never shot during a rain like that. I would have to wonder about shooting in a downpour. I have shot in freezing rain and could not see a difference. As far as figuring things out with math, there are to many variables to trust the result as written in stone.
 
While rain doesn't do anything on shooting a small bullet short distances it's interesting in what it does to a high speed interceptor missile fired in a storm. At 6000 ft/s it looks like the nose is getting sandblasted, losing fractions of an inch in material.
 
I think it's affect is less than all the other variables involved in a typical hunting (not bench rested) shot.

I also think Frankenmauser's statement about the aerodynamic shock waves affect on the rain droplets seems entirely possible.
 
Thanks for the answers guys. The reason I ask is the other day it was raining hard and I took a shot at a coyote 150 yards away and missed him. I thought it was a clear shot just raining, but i guess I just flat out missed him.
 
Driver error?
If we're honest, it probably accounts for more missed shots than anything else.
But in an emergency, any excuse will do nicely. :)
 
I've shot a couple matches out to 600yds through a downpour. The targets start sliding down the face of the cardboard when the paste loosens up. The bullet holes get enormous when the cardboard is saturated. It can pile up on the front sight and fill the rear aperture. Pretty easy to see the wake of the bullet as it heads downrange, but the rain makes no difference on where the bullet goes.
 
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