By Ralph M. Lermayer
A boresighter or collimator can save a lot of rounds. Different studs accommodate a variety of bore sizes.
It’s a safe bet that most hunters expend more ammunition before the season opens than they use the entire season. And, with centerfire cartridges costing $20 to $25 per box, getting a new rifle or new scope on target at 100 yards can be an expensive proposition. It needn’t be. With just a little planning and a big box, you can do it with just a few shots, even with a new rig.
Center Your Reticle
This may be the most important and frequently overlooked step in the initial sight-in process. Turn the windage adjustment all the way until it stops. Direction doesn’t matter. Now, count the clicks until you hit the opposite stop. Go back half the number of clicks, and the reticle will be in the middle of its adjustment range. Do the same for the elevation. Reticles should be as close to center as possible. Off-center reticles, while they appear to be in the center of the scope, can cost a lot of shots. With the reticle centered, you can start the next step.
A boresighter or “collimator” saves time and ammo. A precision metal or polymer stud of the proper caliber is inserted at the muzzle. Atop the stud sits an optical device with a grid pattern in a lens. Adjust your scope’s crosshair to the center of the grid, and you have aligned your scope with the physical center of the bore. It’s by no means a final adjustment, and, sadly, all too many novices think it’s adequate. Usually it will get the shot placement to within 10 to 12 inches at 100 yards.
A large sheet of cardboard or a cardboard box is a valuable aid for initial sight-in.
Several manufacturers make inexpensive collimators. My 25-year-old Bushnell set has done preliminary sighting for hundreds of rifles. If you shoot a lot, they’re a good investment. If not, any gun shop will boresight your rifle for just a few bucks. It’s a good first step, but a long way from a final zero.
With bolt guns or single shots, you can do a fair job of boresighting without a collimator. All it takes is a large cardboard box and a marker. Scrounge the biggest box you can fit in your vehicle, and draw a 2-inch black circle on it. Putting the circle on a white background and taping it to the box makes things easier to see.
Open and remove your bolt, and set the rifle firmly on a rest. Set the black circle at 25 yards, and, looking through the bore from the breech, center the box in the middle of the bore. While keeping the target centered in the bore, carefully move the scope’s windage and elevation until the crosshairs are exactly intersecting the circle. Having a buddy make the adjustments while you check the scope and keep the bull centered helps.
Now, fire one shot. You should be close to center. If not, make the adjustments. Remember, with most modern scopes, it will take 16 clicks to move 1 inch at 25 yards.
If you’ve been able to look through the bore or used a boresighter, you can skip the 12-yard range and go to 25. If your action won’t allow looking through the bore and you don’t have access to an optical boresighter, shooting it in adds a few rounds. A big cardboard box is a must. Once you’ve centered your reticle, set the box target at 12 paces (don’t be tempted to go farther). Fire one round in the center of the bull at 12 yards, then adjust as follows:
Most modern scopes move the point of impact 1/4 inch at 100 yards. Physics are such that that one click will move 1/8 inch at 50 yards and only 1/16 inch at 25 yards. At 12 yards, you may have to crank up to a full turn of the dial to move 1 inch, but do it. Shoot until you’re well inside the 2-inch bull at 12 yards; two shots should do it.
Then move the box to 25 yards and shoot and adjust until you’re dead center in the bull. Two more shots should be adequate. The objective is to be absolutely centered at 25 yards. That will put most rifles close to center or slightly high at 100.
Only when you’re perfect at 25 yards should you move to 100, and there, it should only take a shot or two to get you exactly where you want to be. For most loads, about 2 inches high at 100 will stretch the range to point-and-shoot at 200, and, depending on your cartridge, even farther. Now, take the rest of that box of ammo hunting.
Reprinted from the September 2004 issue of Buckmasters GunHunter Magazine