The sighting in of the hunting rifle, or zeroing as we call it in the gun business, isn't rocket science, but it is a bit of a science.
In modern firearms, virtually all of the issues shooters contended with in the past are distant memories. You may have encountered a few — inaccurate barrels, scopes that move after every shot, triggers that were like dragging a concrete block across pavement and factory ammunition that was sometimes a gamble.
For the sake of discussion, the gun being sighted in is a new bolt-action rifle chambered for the .308 Winchester, with a decent 3×9 scope that was boresighted by the dealer upon purchase.
Before hitting the range, take care of a couple of details that will save time and ammunition.
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First, check all of the screws on the assembly. Loose action or scope mount or ring screws are a common culprit of the rifle that "just won't shoot."
Next, clean the bore with a brass brush and some Hoppe's No. 9 or any other good gun-cleaning solvent. Run dry patches down the bore until they come out clean. Cleaning a new rifle removes the heavy grease applied by some manufacturers to prevent rust during transit and while the rifle is sitting on gun dealers' shelves.
You will need front and rear rests to steady the rifle on the bench. Commercially available rests work well and provide better control than sand bags or a jacket thrown over a backpack. Ideally, the rest set-up allows you to adjust so the rifle sits solidly in the bags, crosshairs on the target.
Whatever rest is used, be sure there is a cushion for the forend. Laying the forend on a solid surface will cause a "bounce" effect that changes the impact of the bullet.
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Other items to bring include targets (pick what your eyes see best), a stapler or thumb tacks, a large piece of cardboard (3×3 foot), and eye and ear protection.
A spotting scope or good binoculars can be helpful and will save some walking. Use ammunition that you will hunt with, because different brands and bullet weights will shoot to a different point of impact.
It will save some frustration to set up the first target on the cardboard at 25 yards. Bore sighting is a less-than-perfect science and starting at 25 yards increases the odds of a bullet hole somewhere on paper with the first shot.
If others are shooting, range etiquette is a requirement. Set up your rests and the rest of your equipment first. Come to the firing line with your action open, muzzle up and lay the rifle in the rests, muzzle pointed downrange. If there are shooters downrange checking or changing targets, wait until they are all back and behind the firing line before you bring your gun up. In fact, anytime there are shooters downrange, open your action and do not touch the gun until everyone is back behind the firing line.
Once the rifle is set up on the rests, sit down behind it and get comfortable. Find the target through the scope and adjust the rests so the rifle is sitting by itself, crosshairs on the target. Shooting from a benchrest is different than shooting in the field in that you do not hold the forend with your support hand. Instead, grip the rifle with your shooting hand and place your support hand around the base of the rear bag. Pull the buttstock tight to your shoulder. With your support hand, manipulate the rear bag to adjust to a perfect hold of the crosshairs on the target.
Center the crosshairs on the target and slowly press the trigger until the rifle fires. There are many ways to describe how a trigger is pressed. The best way I have found to describe this is to "let the gun go off, don't make it go off." When you make it go off, that implies a jerk of the trigger, which results in errant shots not representative of where the rifle is shooting.
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Once you have fired the first shot and you have located the bullet hole, you can start the scope adjustment process. Most scopes have quarter-minute of angle graduations or "clicks." For example, the bullet impacted five inches high and two inches to the left. At 25 yards, those quarter-minute (read as quarter-inch) adjustments move the point of impact one-sixteenth of an inch. That means moving the elevation adjustment 80 graduations or clicks down and the windage adjustment 32 clicks to the right. Make your adjustments and fire another shot, which should be close to the center of the 25-yard target.
Now move your target out to 100 yards. Shoot one shot, which should impact in the vicinity of your aiming point. Shoot two more shots. Now you have an idea how the rifle groups and can adjust the point of impact from the center of the group instead of chasing a single bullet hole.
Years of watching folks attempt to zero hunting rifles has shown me that this "chasing" of bullet holes around the target is what most often derails the process.
Decide where you want the bullet to impact at 100 yards to take advantage of the .308 trajectory. Assuming a 150-grain bullet, a 200-yard zero is reasonable and thus a bullet impact of two inches high at 100 yards is going to be generally correct. Whatever zero you decide, make your scope adjustments from the center of the first group fired.
A cool barrel
Let the barrel cool before you shoot again. Often, even with superbly accurate rifles, the cold barrel shot impacts differently than subsequent shots. For a hunting rifle, the first shot is always going to be a cold barrel shot, and you want your zero to be spot on for the first shot.
Fire the cold barrel shot, mark it no matter where it hits and let the barrel cool again. Fire the second shot and again, let the barrel cool. Fire the third shot and taking the three shots as a group, make your final adjustments based on the center of that group.
What often happens with sighting in rifles is hunters will try to get that perfect center bull's-eye shot and in doing so, make a scope adjustment after every shot. If the rifle shoots 1.5-inch groups, then the bullet may impact a three-quarter-inch high or a three-quarter-inch to the right of that "perfect" zero, and you may never get that absolute center hit.
Rifle accuracy is a product of uniformity and consistency. The ammunition used must be put together with enough uniformity to shoot accurately, which virtually all modern hunting ammunition does.
Shooting the rifle must also be consistently the same. When you sit and wrap yourself around the rifle, do it the same each time. If you hold the buttstock tight on one shot and loose the next time, the impact on the target is going to be different. The press of the trigger, again, must be uniform from shot to shot.
Finally, put on your hunting outerwear and get away from the bench. Shoot from offhand, sitting, kneeling, against a tree branch or over a backpack. Determine from these positions, at what range you can reliably hit an 8-inch paper plate.
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Discipline yourself and, sans a bad case of buck fever, you'll be just fine hunting big game.
Steve Meyer of Soldotna is lifelong Alaskan and an avid shooter. He writes every other week about guns and hunting. Contact him at email@example.com.