When sighting in your rifle, you need to make sure that you begin with a good solid bench and an adjustable but solid rifle rest. Many different guns rests are on the market, from advanced fully adjustable machine rests, to rabbit ear bags and old style shot filled bags. Machine rests generally have, at a minimum, a front forend rest similar to The Rock Jr Shooting Rest. This forend rest is adjustable for elevation so that you can easily and precisely position the rifle. A rear bag is also helpful, even with some machine rests. Other more robust machine rests have fully adjustable front and rear rests, and some like the HySkore Dangerous Game Rest even include a remote trigger, enabling you to fire the rifle without touching it at all.
Consistency is key when sighting in a rifle. Every shot should break exactly the same. You don’t need to be fighting your rest or your bags when setting up for your sighting in shots. Whether you are using a machine rest or sand or shot filled bags, take the time to set up your rest properly so that when the time comes to fire the shot the only thing you are doing is squeezing the trigger. When properly set up on a benchrest prior to the shot, your rifle should be fully supported by the rest and able to remain perfectly centered on your target without any corrections from you the shooter.
Wind flags and pinwheels are very helpful when sighting in so that your shots are not thrown off by the wind. In the absence of wind flags, pay attention to vegetation such as trees, bushes, and grass to see how and when the wind is blowing. One thing you don’t want is to have some shots fired when the wind is blowing while others are shot during lulls in the breeze. Spend some time analyzing the wind and make a conscious decision as to whether you will be firing when the wind is up or during the lulls. Ideally, you should shoot when the wind is down or non-existant. But if that is not possible, you can make accurate estimates of wind speed and direction and use that to adjust the zero on your scope to compensate for the wind. Keep an eye out next week for our article on reading the wind and mirage, where we’ll go into detail on how to read and adjust for these conditions.
Choosing a good target for sighting in your rifle is critical to making the process painless and accurate. Our VisiShot Sight-in Paper Targets feature a grid for easy windage and elevation adjustments, as well as a high visibility background that makes it very easy to see where your shots are hitting the paper. Whatever target style you choose, having a one with a 1″ grid is probably the most important trait that you should look for. When sighting in your rifle at 100 yards, it is easy to adjust elevation and windage because 1 MOA is approximately equal to a 1″ square on your target.
When you’re sighting in a new scope on your rifle, you will first want to get an accurate boresight in order to get your rounds on paper and reasonably close to your point of aim. Performing a boresight on a bolt action rifle is generally quite easy. All you need to do is to pull the bolt and peer down the bore while your rifle is on the bench rest. Next, without moving the rifle, glance through your scope and make a note of where the crosshairs are indicating. Adjust the crosshairs towards the target bullseye and then repeat the procedure, until your scope appears to be aiming fairly close to the center of your boresight.
Reinstall the bolt, and then check your scope. It should be centered perfectly on your target with the bags or rest completely supporting the rifle without any outside support. You should be able to set up on your shooting position behind the rifle and place your shooting hand in position over the trigger, and then remove it so that you are completely hands-off without the rifle changing position at all.
Take three shots to confirm that the rifle is consistent. Your shots may not be near your point of aim, but since the rifle has been bore-sighted they should be on the paper and they should all make a nice tight group. A good tight group demonstrates that the rifle is capable of making consistent and, more importantly, repeatable shots. If your rifle is not shooting consistently, or highly variable wind conditions cause your rounds to drift significantly, it will be very difficult to zero your rifle with any level of confidence. If the wind is calm and the rifle steady on a good solid bench rest, but your rounds are scattered all over the target, it may be time to try another type or brand of ammunition. If you have tried different weights and brands of ammunition and your rifle is still unable to get a good group, it may be time to take your long gun in to an expert gunsmith who can diagnose and hopefully repair the problem.
Once you have confirmed that you are getting consistent shots, it is time to adjust the scope so that the point of aim gives you the desired point of impact. Note that the point of aim and desired point of impact are not always the same. If for example you are sighting in your rifle on a 100-yard range, but you want to have a 300-yard zero, your desired point of impact will be higher than your point of aim by a few inches depending on the cartridge you are firing. By the same token, if you want to sight in your rifle for zero wind but are shooting in a consistent 10mph 90-degree crosswind, you will want your point of impact to be to the right of your point of aim.
There are two ways to adjust the scope to get the point of aim and point of impact the same place. One way is to know how far each click of adjustment moves your point of aim and calculate the necessary adjustments. For example at 100 yards, if your point of impact is 4″ high and 3″ left and your scope adjusts in 1/8 MOA clicks, you would then adjust your scope 32 clicks down and 24 clicks right. The other way is to hold the rifle so that your crosshairs are on your point of aim, and then carefully, without disturbing the rifle in the rest, adjust the scope so that the crosshairs are now over the actual impact holes in your target. This seems counter-intuitive because even though you want the impact to be lower the actual reticle is moving up to meet your actual point of impact. But if you look at the indicators on your turret tubes where you make the adjustments to windage and elevation, you will notice that you are actually moving the point of aim down while the reticle appears to be moving up. The advantage of these methods are that, properly done, they do not use very much ammunition; you can usually get on target with only one adjustment.
When deciding what distance to zero your rifle for, consider the trajectory of your particular cartridge when choosing a point-blank zero. Ideally, you will want a zero that gives you a Maximum Point Blank Range, or MPBR. An MPBR is the zero range at which you will need minimal holdover to keep your round on target. When you are in a hunting situation, there is not always time to grab the range-finder and calculate the exact distance to your target or to stabilize your rifle enough to use your Mil-Dot scope to measure the target size and estimated range. By computing the trajectory of your cartridge, you can calculate the ideal MPBR. For example, let’s say that you are zeroing your 4-16x50mm scope on a Remington 700 chambered in 7mm Remington Ultra Mag. If you have a zero at 350 yards, your maximum variation out to 410 yards is only +/- 6″. For medium game hunting, this will put you at “minute of deer” accuracy for any range between 0 and 410 yards. If we are zeroing this particular combination at 100 yards, the point of impact should be exactly 4.8″ above the point of aim. Ideally, you should confirm your MPBR zero at the actual distance you are calibrating your scope and rifle combination for: in this example we would confirm zero at 350 yards. Find the statistics of the round you are firing and some ballistics tables and play around to find out your MPBR before choosing a distance to zero your rifle.
Images courtesy of Ruger Firearms.