Shooting in rain, wind and weather
If you can cope with it- and dope it- you’re a real rifleman!
You can talk about it and worry about it, but one of the things you can’t do a darned thing about is the weather. If it’s bad, you can always stay home from the range– but in the field, you have to take what’s dished out and make the most of it. I suppose that the ideal conditions for shooting would be clear, calm day, temperature 72 degrees, with a low sun behind you. If you can’t arrange that consistently, then you might as well be prepared for everything else!
Snow and Rain
This one is easy: Precipitation has no measurable effect on a bullet’s flight, at least not over game ranges. Heavy, humid air does offer more resistance, so there is some difference at extreme ranges, as in 1,000-yd. shooting, but over hunting distances it can rain, snow, sleet or hail, and it won’t slow your bullet any more than it will stop your mailman.
Precipitation and fog do limit your range, however, because they limit your ability to see your target. Fog is perhaps the worst. Over the years I’ve sat on many mountains waiting for a fog bank to roll through. Sometimes the game I was watching was still there when it cleared, and sometimes not! Snow squalls can be just as bad. But the real limiting factor with both rain and snow is their effect on riflescopes.
It’s hard enough to see through swirling snow, but a telescopic sight actually magnifies the effect. And then there’s the problem of snowflakes obscuring the scope lenses. Rain is even worse.You can, and should, use scope caps when the skies are threatening. In light rain or snow you can whip off the scope cover and get off a shot before droplets or snowflakes obscure your vision-if you’re quick enough. But if it’s raining or snowing hard enough, or if you need a bit of time to take a shot, you’re going to run into trouble. Bushnell/Bausch & Lomb’s “Rainguard” coating prevents water from collecting and helps tremendouslybut, again, if it’s raining hard enough you’ll still be in trouble. One of the very few times that iron sights are superior to scopes is during a serious downpour or blizzard. Obviously, the range is more limited than with a scope, but you can shoot in rain or snow with irons, and if it’s coming down hard enough you cannot shoot with a scope. So, rifles for wet climates should have auxiliary iron sights, already sighted in, and quick-detachable scope mounts. Light
Light also has nothing to do with the way a bullet flies, but can have a lot to do with how well you see your target. Obviously you must have enough of it so you can properly see your target. The light-gathering capabilities of even a modestly priced scope are such that this is usually no problem during “legal shooting hours.” To me, too much light is a much more insidious problem than not enough! Harsh midday sun creates heat waves and mirage that can cause serious problems, especially if you’re trying to shoot at longer ranges with high magnification. The best cure for mirage is to turn down the power ring!
The worst light problem, however, comes on those rare instances when a low sun is behind your target. Sooner or later this will happen; you’ll shoulder the rifle and be almost ready to shoot, and then you’ll catch the sun in your scope and everything will go black, red or yellow! Over the course of more than a thousand shots at game this has happened to me only a couple of times, but it’s an awful feeling-and there isn’t usually anything to be done about it. There are effective sun shades and filters available, but such an event is hardly planned and few hunting scopes are (or should be) so equipped. The best cure is avoidance; pay attention to where the sun is in relation to your game, and try to plan your stalk so the sun won’t be directly behind the animal when you shoot.
Sometimes it just happens; last year in Ethiopia my buddy Joe Bishop had a shot at a wonderful mountain nyala. The bull was moving across a little valley, and Joe wisely waited until he stopped-except that he stopped with the rising sun directly behind him, and Joe was immediately blinded. He never got a shot off at all, but with some luck we got the same animal the next day. I almost had it happen on an elk this year. By scrunching my head this way and that I got enough of a field of view to take the shot, but when I worked the bolt I got the setting sun in the scope and I lost the animal completely. I was lucky; at exactly that moment he fell over backwards. Good thing, because I’m not sure I could have gotten a clear enough image for a second shot!
Air temperature does have an effect on how a bullet flies. You could say that propellant powders get “hotter” or “colder.” From a mean of 72 degrees you can add or subtract about 25 f.p.s. per 10 degrees Fahrenheit of air temperature up or down. But that isn’t what matters; it’s your starting point that counts.You have sighted in your rifle at a certain temperature. Whatever that temperature is, if you make a radical change in either direction your sight-in will probably not be valid. For instance, if you sight-in at 10
For instance, if you sight-in at 10 degrees in Minnesota in February and go hunting in the Central African Republic, you could have a 90 degree temperature difference, which can mean an increase in muzzle velocity of 200 f.p.s.Your load will be generating not only more velocity but also more pressure, and if you handloaded close to the max in cold weather you could run into serious pressure problems in hot weather. Using the volatile Cordite powder, the British actually offered “tropical loads” for the old Nitro-Express cartridges containing less powder than regulation loads used in England’s cool climate!
The opposite is not quite true, but still a problem. If you go from hot weather to cold-such as zeroing in Florida and going hunting in Alaska you cannot run into pressure problems, but your load will be generating less pressure and less velocity.Your sight-in may be a bit lower, and your trajectory curve will be a bit steeper than you think it is. So, if you combine a radical temperature shift with a fairly long shot, you can run into trouble. Thus, the best course is to always check your zero when you arrive in a hunting area.
Altitude Altitude effect is purely a matter of air resistance; there is less of it in high, thin air. From sea level to 25,000 ft., with a cartridge of about 3,000 f.p.s. muzzle velocity, you can figure your point of impact will go up about 7/8″ at 100 yds. per 5,000-ft. gain in elevation. Again, the elevation change has to be considerable before you will notice the difference. And, again, it depends on your starting point. If you sight-in in Colorado at 9,000-ft. elevation and go hunting along Texas’ Gulf Coast your point of impact will be a bit lower than you think it is. Vice versa, if you sight-in at sea level and go hunting in the mountains, your point of impact is probably going to be higher and your trajectory curve flatter.
This one is not something I worry about too much, but when you talk about extremes the difference is there. When I went to Tajikistan a couple of years ago we all checked our rifles at base camp-at 14,000-ft. elevation.You bet there was a difference, with every rifle in camp shooting 2″ to 3″ higher than its owner thought it should! In China last year, at a similar elevation, I cheated the act: At home, near sea level, I sighted in a bit lower than I wanted to; and, at elevation, my sight-in was just about right!
Without question, the single most significant factor in shooting is wind-and there’s nothing easy about figuring what to do about it. Most of us have heard of the great Marine competitive shooter and sniper known as “White Feather.” Gunnery Sergeant Carlos Hathcock was a great American and a great rifleman. He won many competitive shooting events, and was one of the most successful snipers of all time. I barely knew him, but friends who knew him well tell me that, as fine a marksman as Carlos was, his greatest skill wasn’t “holdin-em and squeezin”em,” but doping the wind-at which he was nearly uncanny.
On the surface, figuring windage sounds fairly easy. Any decent ballistics table will give you wind deflection; you can see at a glance that a spitzer bullet from a .30-’06 will deflect about 8″ at 300 yds. in a 10 m.p.h. crosswind, and about 2 ft. at 500 yds. Double the wind and double the wind deflection. Simple. Except, how do you know?
In order to absolutely know how much the wind is going to blow your bullet, you must know at least four things. The first thing is what the ballistics tables can tell you, more or less: How far off course a certain velocity of wind from a certain direction will blow your bullet at your velocity. The rest of it table cannot tell you. In order for what the table tells you to be useful, you must know the actual wind velocity and the actual wind direction. And then comes the trickiest part of all: Is the wind the same at the target as at the muzzle–and throughout the distance in between?
In a range setting, this is difficult enough, but there are range flags to clue you in. Long-range competitive shooters and even some serious varmint hunters carry pocket-size wind gauges, and these help. But even with range flags and gadgets, precisely determining wind deflection is more of an art form than a science and in the field it borders on alchemy. Very few riflemen are good at it, but those who are-such as Carlos Hathcock was-learn to read subtle clues like waving grass and stirring leaves. Most of us never get that far, and most of us, thank goodness, don’t need to.
The wind effect is a matter of distance, bullet aerodynamics and bullet velocity. The effect begins the instant a bullet leaves the muzzle-but at moderate ranges it isn’t something you need to worry about. If you’re firing a reasonably aerodynamic spitzer bullet at normal velocities-between, say, 2,600 and 3,000 f.p.s. muzzle velocity-the tables will tell you that our “standard” 10 m.p.h. crosswind will move the bullet somewhere between 6″ and 8″ at 300 yds. This should tell you several things, some of which are heartening. Given the size of a big game animal’s vital zone, at normal hunting ranges from the muzzle to maybe 250 yds., you shouldn’t worry about a light breeze. Just hold for the center of the vital zone, and you’ll be all right.
You should know, clinically, that a breeze from behind you or in your face has a negative value, no effect whatsoever. A quartering breeze, coming from a 45 degree angle rather than the 90 degree angle of a straight crosswind, has half value-half what the tables have told you for a pure crosswind. Other angles of wind have either greater or less value, depending on whether they’re closer to 90 degrees or closer to a headwind or tailwind. Again, you don’t need to worry about a mild breeze out to about 250 yds.
Now, if the wind is stronger, and especially if it’s a crosswind, you need to start worrying about it at a shorter distance, perhaps 200 yds. Not long ago, I shot a caribou at just over 200 yds with a .260 Rem. The 140-gr., 6.5 nun bullet I was using is very aerodynamic, but the .260 isn’t a fast cartridge. The wind was extremely strong, at least 30 m.p.h., and it was blowing pretty straight from right to left. Even at that short distance I figured I’d have nearly a foot of wind deflection, so I held accordingly and made as perfect a heart shot as I’ve ever made. If the wind was exactly 30 m.p.h. and the range exactly 200 yds. the table says I should have allowed for 9.6″ of deflection. So I was in the ballpark, but I had plenty of time to think about it!
At 300 yds., you need to start allowing for the effects of even a mild crosswind. At longer ranges even a breath of sideways wind starts to make a difference, and it becomes increasingly difficult to gauge the difference in wind velocity and direction between where you are and where the animal is standing. Shooting at game is not like shooting at targets, nor is it like the shooting that trained snipers do in wartime. The goal is to take the animal cleanly-and not shooting is a perfectly acceptable answer. In a strong wind long range starts at about 300 yds., which might be a practical shot if you know what you’re doing and have time to figure it out. Much beyond that there are simply too many variables. Given knowledge and skill, long shots can be very practical and very ethical on a calm day. But even with knowledge and skill long shots on game in strong wind are neither practical nor ethical, so the real rifleman knows not only when to shoot, but also when the only options are to either get closer or walk away.
Copyright National Rifle Association of America Nov 2002
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