How much does rain or snow affect ballistics?

[1KPerDay]

I am not an experienced rifle shooter. I am pretty terrible actually. I don't have a lot of my rifles sighted in formally; I just shoot them in three gun matches and adjust the sights there. I've never taken my rifles out for "long range" shooting and I'm going to try this weekend. However it's supposed to snow. I'm going regardless, but how bad will my data be affected?

 

[Steve S.]

In my experience, weather (wind, rain, snow, etc) affects shooter ability much more than the rifle. The new generation “plastic” stuff is probably not affected at all, a wood stock might move the zero a tad but it must be poorly finished and get very wet - the ammo should also be little influenced. I think that the shooter is the biggest variable in bad weather.

 

[Sunray]

Snow will affect you more than the rifle. Assuming it's wood stocked and properly sealed. The cold can affect how your powder ignites though. Some powders are temperature sensitive. Magnum primers can help that. It's the only non-powder related time they're useful.
"...don't have a lot of my rifles sighted in..." That's essential. You have to know where your rifles shoot at as given distance. How you sight in depends on the cartridge.

 

[illinoisburt]

Some, but probably not the way you might think. Often bullets impact a little bit higher at long range in the rain than immediately prior to rain starting to fall. Its probably something to do with air density from humidity. Regardless, chances are you aren't going to notice since you are not comparing multiple days of shooting. I haven't heard of rain or snow causing groups to spread though your comfort and abilty to see the target will obviously have an impact on results.

 

[1KPerDay]

so a bullet hitting a raindrop or snowflake or three on the way there doesn't really have a measurable effect?

 

[jmr40]

I've seen studies that say that the shock wave around a bullet in flight will not allow rain or snow to actually ever touch the bullet. I won't say there is concrete proof, but that is the theory. The range I use has a covered shooting area. I've shot several times in both rain and snow and never noted any issues. Humidity can be a factor, as well as altitude and temperature at extreme range. Go to one of the more advanced online ballistics calculators and you can plug in different factors and see that it does in fact change ballistics.

Wind can be a huge factor at longish ranges. And long range depends on what you're shooting. At 200 yards it has to be a pretty stiff wind to have any real effect on most center fire cartridges. But I often shoot 22's at 200+. It has to be almost dead calm to do any good with 22's.

 

[1KPerDay]

Ok that makes sense. supersonic shock wave clears the way I guess?

 

[MCMXI]

Ok that makes sense. supersonic shock wave clears the way I guess?

It sounds good but that's not what the ballistics experts at companies such as Barnes and Berger have found. One such expert recently told me that I should avoid hitting raindrops with bullets when hunting. If a bullet collides with a raindrop while in flight it can have a significant effect on the bullet's stability and therefore its trajectory.

I've seen studies that say that the shock wave around a bullet in flight will not allow rain or snow to actually ever touch the bullet.

So the bullet pushes the air which pushes the rain drop. The rain drop has mass and momentum and will try to resist a change in velocity i.e. acceleration. I think Newton mentioned something about equal and opposite in his third law.

 

[herrwalther]

Wind has more effect on a bullet flight path than rain or snow. I did plenty of rifle qualifications and shooting matches with one or the other falling from the sky. Bullets always went where I wanted them as long as I did my part.

 

[bikemutt]

Here in the great northwest we read the rain. Everyone has a calibrated, empty Vienna sausage can which is set in the rain for exactly 5 minutes prior to taking a shot. Then, for every 1" of water in the can, we aim 1" high on the target.

 

[z7]

In 3 gun (400yds or less) with an ar15 you may be cold wet and uncomfortable but the bullet will still fly where you tell it

 

[CLP]

"How much does rain or snow affect ballistics?"

Without intending to sound like a smart aleck, I'd say it depends on how many rain drops or snowflakes any given bullet in flight hits, other weather factors (wind, temp, humidity), and bullet profile. The latter is obviously of great importance and is why pistol caliber rifles and blunt, round-nosed bullets like 30-30 and 35 Rem are popular woods or "brush" guns since bullets with those profiles purportedly display less trajectory deflection when hitting twigs, stems, etc.
Another consideration is how much distance exists between the droplet/flake impact(s) and the target.
All of that considered, there are some really cool slow-mo videos floating around in the vitrual aether showing bullets hitting droplets of liquid sustaining marked deformation upon impact. I'll see if I can track one down and link it.

Update:
This is a popular Werner Mehl / Kurzzeit video. Okay, the whole entire video is just pretty danged cool. But the video I was referring to starts at 1:59.

And while watching this I had a terrible college physics flashback. I recall there being like a whole chapter on trajectory. Other factors I didn't previously mention would be (and this isn't in any order of importance): velocity of both the bullet and the drop/flake, density surely comes into play (likely a constant with rain drops, but with snow?), size of drops/flakes (skier's flakes vs. snowballer's flakes), and the individual trajectories of both the bullet and drop/flake prior to collision. And where on the bullet the drop/flake collides with it (nose vs side or tail of the bullet)

There's probably other factors- we have any physics gurus that want to lecture more about this (since all physicists love to lecture...)?

One final remark...sorry, but I just can't keep quiet at this point. Despite the video being B&W, the liquid seen on the video at the 1:59 time-mark is opaque and can be assumed to be something other than pure water (or water approximating the density of rainwater)- so we don't know its density. Incidentally, it looks like paint. And we don't know the composition of those bullets (plated vs jacketed, alloy composition, etc) or the other aforementioned variables. All you can say is that the impact between that particular liquid droplet and bullet caused deformation. If it was a rain drop, it could possibly cause less deformation or maybe even none at all. The implication in either case being that the droplet impact and any subsequent deformation cause a deviation from the intended trajectory of the bullet.

Incidentally, I have no practical knowledge of any of this. I tend to remain inside when it rains/snows.

 

[FL-NC]

Regarding in flight ballistics, there is no effect from rain or snow. Wind is the big one. Temperature, humidity, barometric pressure, and altitude all have effects.

 

[CLP]

Regarding in flight ballistics, there is no effect from rain or snow. Wind is the big one. Temperature, humidity, barometric pressure, and altitude all have effects.

I don't think that's correct. Even if the argument that a bullet's "shock wave" displaces a rain drop and that the rain doesn't physically impact the bullet itself, there will still be a deflection in trajectory because kinetic energy from the bullet has to be expended to push aside that droplet and that expenditure will be asymmetric (existing on only one side of the bullet). There may be a completely different set of rules for subsonic vs supersonic bullets.
However, there's no doubt wind plays a major role in drift. But I'd argue that if all other variables were controlled for, a guy shooting at target 100 yards away in a thunderstorm will have a wider grouping than a guy shooting in the absence of rain-- again, controlling for all other variables and if a statistically significant number of shots was fired in each situation. So I wouldn't agree that rain has "no effect". A single rain drop- I would agree it has no appreciable effect since the rain drop is in contact with the bullet for so little time and itself has so little mass relative to the bullet. But a single rain drop is not "shooting in the rain", a condition in which a bullet will be impacted by innumerable rain drops which have a cumulative effect on trajectory.
But I don't shoot in the rain and I freely admit I could be completely wrong or that any such impact in deviation is so minute that it only exists on paper in calculations.
And one last thing- I know there's a lot of cases of people claiming rain has had no impact on their groups. However, there are many variables and biases that aren't accounted for overall and anecdotal information is weak at best. If there are two different scenarios where all variables are identical except there's heavy rain in one- I could easily see how the shooter in the rain might even have a tighter group since wind can be much more easily read when it's raining than when it's not. The only way this can be satisfactorily put to bed is for a proper experiment to be conducted.
Personally, I rarely shoot past 100-200 yards and really only struggle with wind drift in 17 HMR since it's so sensitive to wind and I usually shoot in good conditions. And it may be because of my background, but I might trying to account for something that is theoretically correct but rarely if ever seen in practice.

 

[VoodooMountain]

My guess is that the bullet is moving so fast and spinning fast enough that rain drops and especially snow flakes would act more like humidity as opposed to throwing a stone st a snowball.

Though I suppose in a heavy rain the point of impact would be a smidge lower? Time of flight matters but I can’t imagine rain having a large impact in most situations when the bullet goes from barrel to paper in .6 seconds.


I guess this would be easy enough to test though.

 

[cdb1]

As badly as I shoot .... not at all.

 

[CLP]

My guess is that the bullet is moving so fast and spinning fast enough that rain drops and especially snow flakes would act more like humidity as opposed to throwing a stone st a snowball.

Though I suppose in a heavy rain the point of impact would be a smidge lower? Time of flight matters but I can’t imagine rain having a large impact in most situations when the bullet goes from barrel to paper in .6 seconds.


I guess this would be easy enough to test though.

Well what's a heavy rain? A misty drizzle in Seattle that you ponder over from inside a cafe or a an Alabama thunderstorm with raindrops as fat as the people that splash and sting your eyes when they hit your face? THere's an incredible amount of variables to account for. Oh, and this is interesting- consider this is a second-hand citation since I don't own a copy, but apparently the NRA Fact Book reports that POIs tend to be higher when it's raining because of a decrease in the barometric pressure. It's confounding.

 

[JeffG]

I am not an experienced rifle shooter. I am pretty terrible actually. I don't have a lot of my rifles sighted in formally; I just shoot them in three gun matches and adjust the sights there. I've never taken my rifles out for "long range" shooting and I'm going to try this weekend. However it's supposed to snow. I'm going regardless, but how bad will my data be affected?

Once upon a time......I shot a string of slow fire at 600 yards during a match in the Marine Corps with a match M14. I was well practiced from the previous weeks of training. Just when I got all trussed up with my sling, and dropped to the ground, the heavens opened up, and it began to POUR. I looked at my coach, and he said "shoot 'em out". So I did; 10 rounds, change magazines, 10 more rounds. The vibration of the action kept the peep sight free of water. I was soaked, and I was laying in standing water when the string of fire was over. I dropped 2 rounds close into the 9 ring, all others in the bull. I never let weather bother my shooting again. Your shooting record book, to include target photos can be used to compare results, but I would shoot confidently.

 

[1KPerDay]

That's a great story. I'd love to be able to do that with my M1A.

 

[1KPerDay]

As badly as I shoot .... not at all.

LOL that's about how I feel... I probably shouldn't even be asking. I'll be lucky if I can hit the paper at 100.

 

[VoodooMountain]

Well what's a heavy rain? A misty drizzle in Seattle that you ponder over from inside a cafe or a an Alabama thunderstorm with raindrops as fat as the people that splash and sting your eyes when they hit your face? THere's an incredible amount of variables to account for. Oh, and this is interesting- consider this is a second-hand citation since I don't own a copy, but apparently the NRA Fact Book reports that POIs tend to be higher when it's raining because of a decrease in the barometric pressure. It's confounding.

That would fall in line with rainnacting more like humidity I guess?

Next time I have a chance I’ll go out and shoot a few familiar loads in the rain

 

[Klint Beastwood]

so a bullet hitting a raindrop or snowflake or three on the way there doesn't really have a measurable effect?

100% humidity on my kestrel (raining) and only a .003 mils difference then at my usual shooting conditions.
Not much effect at all externally. Internally is a different story. Don’t get snow in your barrel

 

[FL-NC]

I don't think that's correct. Even if the argument that a bullet's "shock wave" displaces a rain drop and that the rain doesn't physically impact the bullet itself, there will still be a deflection in trajectory because kinetic energy from the bullet has to be expended to push aside that droplet and that expenditure will be asymmetric (existing on only one side of the bullet). There may be a completely different set of rules for subsonic vs supersonic bullets.
However, there's no doubt wind plays a major role in drift. But I'd argue that if all other variables were controlled for, a guy shooting at target 100 yards away in a thunderstorm will have a wider grouping than a guy shooting in the absence of rain-- again, controlling for all other variables and if a statistically significant number of shots was fired in each situation. So I wouldn't agree that rain has "no effect". A single rain drop- I would agree it has no appreciable effect since the rain drop is in contact with the bullet for so little time and itself has so little mass relative to the bullet. But a single rain drop is not "shooting in the rain", a condition in which a bullet will be impacted by innumerable rain drops which have a cumulative effect on trajectory.
But I don't shoot in the rain and I freely admit I could be completely wrong or that any such impact in deviation is so minute that it only exists on paper in calculations.
And one last thing- I know there's a lot of cases of people claiming rain has had no impact on their groups. However, there are many variables and biases that aren't accounted for overall and anecdotal information is weak at best. If there are two different scenarios where all variables are identical except there's heavy rain in one- I could easily see how the shooter in the rain might even have a tighter group since wind can be much more easily read when it's raining than when it's not. The only way this can be satisfactorily put to bed is for a proper experiment to be conducted.
Personally, I rarely shoot past 100-200 yards and really only struggle with wind drift in 17 HMR since it's so sensitive to wind and I usually shoot in good conditions. And it may be because of my background, but I might trying to account for something that is theoretically correct but rarely if ever seen in practice.

Live fire testing we did at the sniper school to confirm other tests with multiple weapons proved no effect.

 

[22250Rem]

I used to shoot year round at my clubs range ( still do; but not as often when its rain or snow). The firing points on the rifle range have a roof over them so I was able to shoot in all kinds of inclement weather and just get rained / snowed on when going to change targets. At 50, 100, or 200 yards I've never noticed any difference with any of my rifles in rain or snow. I've wondered about shooting in those conditions because this question does come up occasionally but based on my experience with my rifles, at least out to 200 yds. anyway; is that there's not enough ( if any) difference to worry myself about it.

 

[Skylerbone]

All of those quarks your bullet is striking should not be dismissed! If you had to look up that word you're not a physicist. Perhaps a ballistician could answer the question scientifically as well. The human brain dislikes the unknown and would rather create an answer than face uncertain reality.

Knowing this, and as a year-round shooter, I will attest to having no clue beyond "seemingly no effect". If I tracked such things I could keep a closer log of my personal experience but all other factors simply aren't equal and that is why, despite in-depth scientific fact, my brain will also gravitate toward the group's shared experience and say fuhgedaboutit.

What if any affect will be noticed by you at 100 yards? As much as you care to add to the story if'n your group size is really bad. That's the time to lay that trump card down and tell folks you were shooting in bad weather.

Post up some pics and let us know how you did.