Thursday, April 29, 2010

Compensating For Wind At Rifle Competitions

In the past few weeks, we've gone over how to sight in your bolt action rifle, and discussed how to navigate wind and mirage. After practice at the range, you're probably getting pretty confident in your ability to place rounds in the X ring at various distances and may be considering entering a High Power, F Class, or other long range rifle match. How do you apply these concepts under the pressure of competition and the time constraints when it's your turn on the firing line?

Windsock image courtesy Elizabeth/Table4Five, licensed under Creative Commons
To start with, relax. It's normal to have "competition jitters" at your first match, but take a few deep breaths and try to relax. Talk to other competitors and ask questions. Most long range shooters are more than willing to help newcomers, and you'll be amazed at the amount of knowledge you can pick up from an experienced rifleman. Don't hesitate to confirm your wind and mirage observations with your fellow shooters. Target shooters are a friendly bunch, and most won't hesitate to give you their opinion on the methods they use to measure and compensate for wind and mirage.

From the moment you arrive at the range, begin observing the prevailing atmospheric conditions. Once your squad is called to the line, set up your equipment and immediately start analyzing the wind and mirage. You may not be able to use your scope prior to assuming your firing position, but you can observe wind flags for clues about wind speed and direction. Make a decision about what the prevailing conditions are and how you will initially adjust your sights or scope. This initial observation shouldn't be set in stone; wind conditions can and do change and you may need to further adjust your windage after firing your sighter rounds.

Some novice shooters try to take their shots during lulls in the wind. Keep in mind that wind conditions can change rapidly. This rookie mistake relies on the shooters ability to get every shot fired during identical conditions, a nearly impossible task. Accept the wind and mirage for what they are and instead determine what speed and direction is the predominant condition, then bracket the conditions by firing your sighter rounds and noting the maximum and minimum drift. After adjusting for the average drift, fire your rounds for record by targeting the windward side of the X ring. High power rifle 10 rings are 2 MOA in diameter. By bracketing the conditions and adjusting your scope or sights for the for the average wind speed and mirage, you should be able to fire all of your rounds at the windward side of the 10 ring with confidence that most rounds will land in the 9, 10, or X ring (assuming you can shoot a 1 MOA group of course). For example, with a wind blowing 5 - 10 mph from left to right, depending on the cartridge you are firing, you might adjust your aim 4 MOA to the left. This splits the difference between the 2 - 6 MOA the wind will move your bullet, so that when the wind gusts it will simply move your bullet from the windward side of the 10-ring to the leeward side.

In some cases, the wind changes direction frequently, at times blowing left to right and at others right to left. The key to shooting well in these conditions is consistency. If you are set up for a left to right breeze and it keeps switching right to left, simply be patient and shoot what you're setup for. This is where your consistent observation of the wind conditions prior to approaching the firing lines comes in. You will need to be able to identify an inconsistent wind that changes direction frequently versus a wholesale change in wind direction.

When shooting during slow fire, use a notebook to record the wind conditions and any adjustment or hold and mark the impact of each shot on a sketch of your target. You'll have plenty of time during these slow fire stages to determine how the wind is affecting your trajectory and how well your windage adjustments are compensating for drift. During competition, keep an eye on the upwind indicators; flags, trees, grass, etc. These upwind indicators will give you a few seconds warning of changes to wind speed and direction. Any significant change from the wind and mirage conditions that you have already compensated for may result in a shot flying wide, so if possible wait to see if the change is just a temporary shift or if it is a prolonged change of the prevailing conditions.

During high power rapid fire stages you will only get two opportunities to compensate for changing wind conditions: once before your string of fire and once during the reload. Some shooters prefer to use holdover rather than take the time to adjust for a slight change in wind speed or direction. While it helps you maintain a better sight picture if you adjust your windage rather than hold, the risk of throwing your string off target can outweigh the benefits during rapid fire stages. Unless there is a dramatic change in the wind, it's far better to stick with your bracket and shoot the "safe" side of the 10 ring.

If the wind is fitful, changing direction and speed between your firing position and the target, give the most value to the wind closest to your target. Your bullet is traveling the slowest in the last couple of hundred yards before your target, which gives the wind the most time to affect its trajectory. A .223 bullet takes only 1/10th of a second to travel the first 100 yards of a 600 yard shot, but takes three times as long to travel the last 100 yards. this gives the wind near the target three times as much effect as the wind near the firing line.

Being able to accurately read and compensate for the wind is an important skill, but at the end of the day, there is no replacement for practice. Some shooters spend hours hand loading match ammunition, trying to squeeze the last 1/4 MOA out of their favored cartridge. Instead of fretting over the accuracy of your ammunition, that time would be better spent behind the rifle getting trigger time. In almost every case the rifle and ammunition are far more accurate than the person pulling the trigger. It does you no good to have a rifle and ammunition that can shoot a 1/4 MOA group if you can't keep it within 1 MOA shooting off hand. Shooting full power loads for practice can get expensive, but there are alternatives. If your local range doesn't have targets farther than 100 yards you can still get good practice reading wind with a .22 rifle at distances from 50 to 100 yards. Even setting up a small pellet rifle range in your basement will result in improved match scores by giving you more experience obtaining a good sight picture. By focusing on your basic marksmanship skills rather than your equipment, you will be better able to shoot in a variety of wind conditions.

No comments:

Post a Comment