Longer-range rifle shooting isn’t easy, and it’s more difficult when the wind is blowing. Here’s a head start on learning to determine and correct for environmental conditions.
Glen D. Zediker
When I very first started up working with Midsouth, I had quite a few folks writing and requesting to learn more about shooting, and, specifically, NRA High Power Rifle competition. It did my heart good to learn that these folks knew my name and associated it with that venue. HPR has been the main focus of my shooting career. That background is the reason I began the “Shooting Skills” portion of the newsletter, and for a few installments upcoming I will oblige to further go a little deeper.
That’s one of the first things that comes to anyone’s mind when High Power is the topic. Describe the tournament course of fire and when you get to “…then 20 rounds at 600 yards…” that one creates a tad amount of anxiety in the imagination.
First comment is almost always, “How do you shoot that far with iron sights?” And that’s easy: the target is huge! The aiming black or bullseye is scaled up to a diameter that provides a clear reference to position the sight. And then the next is, “What about the wind…” Well. First, it’s really not that difficult. Second, it’s also really not that easy. You need to know a few things, so here’s where we’ll start.
To be sure, organized competition is not the only venue where learning to shoot in the wind helps. It’s a skill that anyone who fires across more than 200 yards worth of real estate needs to develop. It’s a little easier in a shooting contest because there’s some feedback to work with: holes in the target.
There are two influential components to wind, and, “influential” means the effect on moving the bullet. Speed + Direction. There are good ballistic programs and apps now that provide approximate values: input the points (bullet ballistic coefficient and wind speed) and get a fast answer. That answer is liable to be incomplete, and by that I mean it’s rare indeed to dial in the given solution and hit the target. One at a time we’ll look at other factors which, taken all together, will get you a whole lot closer on that first shot.
The better apps allow also for angular extrapolation, and that is important. Otherwise, if you’re looking at a table the drift amount will be for a “full-value” wind, which is blowing at a right angle or perpendicular to the rifle barrel. Straight crosswind, 9-o’clock to 3-o’clock, or vice versa. If there’s an angle involved, reduce the amount of anticipated drift based directly on the angle: if the wind is angling from, say, 8-o’clock to 2-o’clock we’d say that was a “half value.” From 7-o’clock to 1-o’clock that’s closer to a “quarter value.” So if the drift table says 12 inches, half is 6 and a quarter is 3. At 600 yards it doesn’t really matter if the wind is coming in or going out: head- or tail-winds have little unique influence on the bullet.
And speaking of, there is a different set of “rules” for 1000 yards and more, or maybe I should say different applications or emphases. The reason is because the bullet has slowed down that much more.
At minimum you’ll need to know the advertised BC or ballistic coefficient of your bullet and its muzzle velocity. I wish I didn’t have to continually offer up all the “maybes” and qualifications, but I do because they exist. The actual realized or demonstrated BC of any bullet varies day to day, often during the day. Velocites can also change a bit for varied reasons. However! None of this honestly really matters to the score and that is because the combination of BC and velocity just gets us “close” and finds a place to start from. Ballistics is a finite science, but there are no finite results. With experience you’ll see that BC is really mostly a way to compare different bullets; its value in making truly accurate and finite corrections is limited.
All this is affected by air density and that’s a whole other topic for a whole other time. And there’s another list of inputs that each have an influence, and that, again, is why this little series is a series.
Dang. There’s a lot to talk about and I’m pretty much out of space. That’s what “next times” are for. I’ll keep this going long enough to provide some genuine help.
Understand that arriving at a sight solution that keeps the shots in the center involves more input that any “drift/drop” equation can provide.
Information in this article was adapted from material in several books published by Zediker Publishing. Glen Zediker has worked professionally with some of the greatest shooters on the planet, and he does pretty well on his own: Glen is a card-carrying NRA High Master and earned that classification in NRA High Power Rifle using an AR15 Service Rifle. For more information, please check ZedikerPublishing.com