How to Sight-in a Hunting Rifle
by Chuck (Onehorse) Tarinelli
When it comes to sighting-in a rifle/scope combination, hunters can choose from a variety of laser boresighters to help get those first shots on the paper. These precision instruments work well with all kinds of actions, but since most long range shooters still use bolt action rifles, I’ll explain how bore-sighting can be done without a laser. This can only be done with a bolt action because you have to remove the bolt and actually look through the bore.
After the bolt has been removed, set up a target at 25 yards and put your rifle on a good solid rest so that it won’t move after you line it up. Sand bags and adjustable forearm rests work well for this. Look down the barrel while you adjust your rifle and bags until the bull of the target looks exactly centered in the muzzle of the barrel. (You will be looking down the line-of-departure.) Without moving anything, look through your scope to see where the cross hairs are located on the target. Most likely they will be off the bull. If you have to make a left or right adjustment, and your base is capable of making them (usually by loosening one of the rear mounting screws on one side of the base and tightening the opposite screw) do that first. Remember to keep peeking down the barrel while you do this to be sure the bull is still in the center of the bore. Make elevation and all final adjustments by using the turret screws of the scope. As you do this, it will look like the bull is moving closer and closer to the center of the cross hairs.
When the bull’s eye gets centered on the crosshairs, take a shot at twenty-five yards. If you’ve done everything right, you should hit the paper. Make any other scope adjustments that are necessary to hit the bull, then try shooting at a new target at 100 yards. You should, at least, be on the paper if not in the black. During this whole process, it helps if you know how the minute of angle adjustments on your scope turret screws work. Some are quarter inch meaning that one “click” will move the impact of the bullet one quarter of an inch @ 100 yards. So, for example, if your bullet is 3 inches to the left at 100 yards, you would have to move 12 “clicks” to the “R” direction. Keep in mind that because your twenty-five yards target is four times closer than the one hundred yard target, you will have to quadruple your adjustments when you are shooting @ 25 yards. That is, if you are hitting 3 inches to your left @ twenty-five yards, you will have to move 48 “clicks” to the “R” direction to hit the bull. Of course, the same calibration will apply to your scope’s “up/down” adjustments. You will have to take several shots, usually a group of three at a time, to determine in which direction(s) you need to adjust your scope. For hunting situations, the traditional way to sight-in is to have your three shot group center on a spot two inches above the point of aim at one-hundred yards. Here’s why:
If you remember the principles of trajectory and optics as explained earlier, you will understand that by sighting-in two inches high at one hundred yards, the high point of the trajectory (top of the curve) occurs at about that distance, (illustration below). This high point is referred to as the mid-range trajectory. When a typical hunting caliber is sighted-in to hit about two inches high at 100 yards, the first time it crosses the line-of sight will be at approximately 20 yards. The next time it crosses the line-of-sight will be at about 200 yards and still in the ascending part of its trajectory. With your sights set up this way, you can hold right on your normal aiming point out to approximately 220 yards. You may strike your target an inch or two above or below your point of aim, but you can still expect to make a clean kill at any distance within that range. That kill zone is known as “point-blank-range”. As the bullet gets beyond that range, it continues to drop at an ever-increasing speed which will necessitate some compensation in aiming.
(All trajectory illustrations in this article are approximate. Hunters must determine the performance of their specific caliber/load/rifle/scope combinations.)
When a hunter sights-in a rifle for 100 yards, (illustration below), the mid-range trajectory occurs before the bullet reaches the 100 yard mark. Although the bullet will strike the point-of-aim at 100 yards, it will be on the descending side of its trajectory. In effect, the parabolic arc of the trajectory has been tilted downward as compared to that of the rifle which is sighted-in for 200 yards.This significantly shortens the point-blank-range and makes it necessary to use hold-over aiming points at much shorter distances than when the rifle is sighted-in for 200 yards. Also, the space between the hold-over aiming point and the point of desired bullet impact become larger and more difficult to determine. In this case, the hunter is severely limiting his or her ability to take most long range shots.
Certainly, a 220 yard shot is hardly short range, but this article is about shooting game at long range, and although every hunter must define just what that means in terms of his or her shooting ability, for our purposes, we’ll arbitrarily set this to be somewhere around 400 yards. I know only a couple, (literally two), of hunters who have the skills to take shots at that range, (and unfortunately many who just THINK they can). I hasten to add, and am not in the least bit embarrassed to say, that I don’t take shots at that range. Under most field conditions, I usually stop shooting a little beyond 300 and usually do everything possible to get within 200 – as close as possible, really. But any distance that a hunter might set as a personal shooting limit that is beyond point blank range will require some sort of hold-over when aiming. This is where plenty of practice at the shooting range becomes extremely important.
With so many different calibers and bullet combinations out there, it’s simply not possible for any article on shooting to give specifics on precisely where each and every rifle should be aimed to strike the bull’s eye at every practical shooting distance. Even the rifle ballistics tables that are found in most reloading guidebooks usually give only approximations as to how far a bullet might drop at various distances. Of course, if you used the same bullet (brand, style, weight, shape) and could duplicate the exact speed of the bullet used in the test, your shots would match the data given in these tables. Even so, nothing takes the place of actual shooting. Not only will this determine your personal shooting distance limitations, but it will improve your skills, and most importantly increase your confidence.
To be successful at shooting game at long range, you must learn what your rifle and you are capable of doing. At first, use sand bags on a good steady rest, and RECORD how far your bullet drops and how far above the desired point of impact you need to aim at various ranges. Once you’ve established what your rifle can do, start shooting under simulated field conditions. Use the bipod with which you will be hunting, or practice shooting with your rifle resting on your backpack. Shoot from the prone, sitting, kneeling and standing positions, and note what effect these different positions have on your practical shooting distances. (I have listed these positions from most to least steady.) Don’t just go to the range on warm balmy days – try shooting when it’s cold and windy just to see how all these factors effect your accuracy at long range. Throughout this process, always use the same bullets with which you plan to hunt. This kind of work will pay big dividends when you are hunting. Perhaps the payoff will be a nice trophy, or maybe just the satisfaction of knowing that you did the right thing by NOT shooting at that fine animal because things just weren’t right!
This whole process of sighting-in, practicing at different ranges and under various conditions does more than establish a hunter’s physical shooting limits. It establishes his or her confidence zone. I use the word “zone” instead of range because I would like the you to think of this as much more than a specific measurable distance within which a hunter can reasonably and ethically shoot. It is actually a state of mind – a super-positive attitude. Any shot that is taken inside of this zone should be considered more than just doable, but a certainty, a “done deal” even before the trigger is pulled. Anything less than a perfect hit inside this zone should have the hunter wondering if something went wrong with his or her equipment, or if the world shifted on its axis just as the trigger was pulled. That’s just how certain a hunter should feel about any shot taken with this confidence zone.
So, now that your rifle is sighted-in and you’ve established your confidence zone, are you ready for opening day? Not quite. Knowing where to aim (dead-on, or hold-over and how much) at different known distances at the shooting range is very well and good, but none of that means much when looking at an animal which is way out there at some unknown distance in the field. So, next we’ll look at how to accurately judge distances of game animals in the field, but, as always, we’ll start by taking another trip to the range.
Next, we’ll look at how to determine the distance of long range shots.