As an ethical hunter, you want to make sure that your rifle is properly sighted in before your hunting trip starts. Here’s a foolproof way to sight in your rifle.
How It's Done by Chuck Hawks
After you have firmly mounted a scope on your rifle and focused it to your eye, bore sight the rifle. Use a bore collimator or do it the old fashioned way, but get it done before you fire the first shot from your rifle. See my article "How to Bore Sight A Rifle" for further details.
I am assuming a telescopic sight because this article is about sighting-in a hunting rifle and all game animals, small or large, deserve your best shot, which cannot be delivered with iron sights. In any case, the iron sights typically supplied with new factory made rifles are so crude that you would probably spend more money on ammunition attempting to sight them in than you would on an economical scope. If you are reading this article in hopes of learning how to hammer the factory rear sight to and fro in its dovetail slot to adjust for windage, you are going to be disappointed.
Once your scoped rifle has been bore sighted for 100 yards it is time to go to the rifle range, which should offer at least 25 yard and 100 yard (or 100 meter) firing positions. If your local range doesn't, find one that does or head for the hills with your portable shooting bench and measure the required ranges as accurately as possible.
Start at the 25 yard position. Put up a large paper target. I usually use an NRA 100 yard small bore rifle target, which has a large black bulls-eye. Get really comfortable on the shooting bench, so that none of your muscles are cramped or in tension. Bring a pillow or a folded-up blanket to sit on (as required) to get your head and shoulders at a comfortable height at the bench rest.
When you are seated and comfortable, position one or more sandbags on the table so that you can comfortably rest the forearm of your rifle (or the hand holding the forearm of your rifle) on them. If you don't have real sandbags, an 8-10 pound bag (or two) of kitty litter works well. (I duct tape the ends of "Jonny Cat" brand bags of kitty litter and they last for many trips to the range.) I cover the Jonny Cat bag(s) with an old blanket for comfort, and to protect them. A commercial rifle rest (I have heard that Outers makes a good one) is probably better than sandbags, but sandbags (or kitty litter) are cheaper. Never rest any part of a rifle, and particularly the barrel, on a hard surface. On recoil the rifle will jump away from a hard surface, giving you a false point of impact.
Because I will be holding the forearm of my rifle in my hand in the field, I do the same at the range. I rest my hand over the sandbag and grip the forearm of my rifle in my hand, just as I would in the field. Try to hold the rifle as firmly as you would in the field. Changing the way you hold a rifle will change its point of impact, so I try to hold my rifle at the range as much as possible as I will be holding it in the field.
Remember that you are sighting-in a hunting rifle. You could probably get somewhat smaller groups by minimizing all human contact with the rifle, especially by letting the sandbags or rifle rest entirely support the forearm. Small groups are desirable, but in this case getting the point of impact correct is even more important. You can always shoot for the smallest possible group size later.
Anyway, by now you should be in a steady position at the shooting bench with the rifle pointed at the 25 yard target. If you are using a variable power scope, set it to the highest practical power. In other words, the highest power that delivers a sharp, clear image. This may not be the maximum power. Many scopes look better slightly below their maximum magnification. For example, the view through a 3-9x scope may look better at 7x or 8x than it does at 9x.
Now load one round into the chamber and prepare to shoot. Put the crosshairs directly on the center of that big, black bull. Before you shoot, close your eyes for 10 seconds and then open them. Did the crosshair drift off the center of the target while your shooting eye was closed? If it did it means that your muscles are under tension trying to keep the rifle on target. Shift your position slightly until you can close your eyes and find that the rifle is still aimed directly at the point of aim when you open them. Now your muscles are properly relaxed and you are in a position to do your best shooting. Go through this little routine before you fire every shot.
Carefully fire one round. Call the shot. If the crosshair was on the center of the target when the gun fired, you don't need to shoot again. If it wasn't, mark that hole as a flyer and shoot again. Get a perfect surprise break.
Okay, examine the target and find the bullet hole. You can probably see it through your rifle scope, and certainly through your spotting scope. (You did bring a spotting scope, didn't you?) Even though you bore sighted your rifle the bullet hole is probably not going to be in the center of the target at 25 yards, but at least it should be somewhere on the paper. Measure (or at least accurately estimate) its distance from the "X" in the center of the bull. Let's say, for example, that single perfect shot hit 3 inches high and 2 inches to the left of the center of the target.
Adjust your scope the number of clicks or increments required to move the point of impact to the center of the target. For example, let's say the instructions that came with your scope advise that each click moves the point of impact 1/4 MOA, which is 1/4 inch at 100 yards. Fine, but since we are shooting at only 25 yards, we will need to multiply the number of clicks by 4.
To move the point of impact down the required 3" at 100 yards would require 12 clicks (four clicks per inch). At 25 yards, remember, we will have to multiply the number of clicks by 4, so turn the elevation adjustment in the down direction 48 clicks (12 x 4 = 48). It is a good idea to go a little past the new setting and then come back whenever adjusting a scope. I'd turn, say, 50 clicks and then come back 2 clicks for a total of 48 clicks down. This helps settle the adjustments of many scopes. I also tap the adjustment dials after setting them, for the same reason.
Now adjust the windage. You need to move the point of impact 2 inches to the right, which at 100 yards would require 8 clicks. At 25 yards that means 32 clicks (8 x 4 = 32). Turn the windage adjustment a total of 32 clicks to the right (usually marked "R" on most scopes).
Okay, now get back into that comfortable position and fire one more perfect shot at the 25 yard target. Ideally, if the scope's adjustments are accurate, it should hit inside the "10-ring" of a 100 yard small bore rifle target. If it does, your preliminary 25 yard sighting is close enough. No need to waste ammunition getting it perfect. You will do that at 100 yards.
If the second shot is not within an inch of the center of the target, you will have to adjust the scope again. By the third or fourth shot and adjustment of the scope the bullet should be landing inside of the 10-ring. If it isn't, something may be wrong. Check the scope mount screws for tightness. They must allow absolutely no movement of the scope under recoil.
Let's assume that your rifle is now hitting within an inch or less of the point of aim at 25 yards. Great, now it will at least be on the paper at 100 yards. Hopefully, it has only taken 2 or 3 shots to achieve this. The rifle's barrel is probably not too hot, your shoulder is still in good shape, and you haven't wasted a lot of ammunition.
Now put up a 100 yard target. You can use the 100 yard small bore rifle target, but I prefer the Outers "Score Keeper" target. It has a central bull's-eye and 4 smaller bulls, one in each corner (which I ignore). Best of all, it is overlaid with 1 inch grid lines, making it easy to see how far your bullet holes are from the point of aim using only your spotting scope--no need to measure. This saves a lot of steps when shooting at 100 yards.
Wait until your rifle barrel has cooled to the ambient temperature (keep it out of the sun), and then get back into your comfortable bench rest shooting position. Remember to close your eyes before you shoot to check for a perfect, tension free hold. This time you will fire 3 shots, slowly and very carefully, at the exact center of the 100 yard target. Take your time and make each shot a perfect surprise break. Call your shots and check each one through your spotting scope. That way, if you call a flyer, you will know which bullet hole to disregard. Re-shoot any flyers so that you have 3 good shots on the target.
Now estimate the center point of impact for the three bullet holes. If you have an accurate rifle and shot it well, they should be within about a 3 inch (or smaller) circle somewhere on the 100 yard target, so this should not be too difficult.
Now is the time to use what you learned by studying the "Expanded Rifle Trajectory Table" on the Tables, Charts and Lists Page. If you did your home work before leaving for the range you should know where you want your bullets to hit at 100 yards to take full advantage of your rifle's maximum point blank range (MPBR).
For many typical long range rifle calibers, such as the .243 Winchester with a 95 grain bullet, 6mm Remington with a 100 grain bullet, .25-06 with 100-125 grain bullets, .270 Winchester with 130-140 grain bullets, 7mm Magnum with 140-160 grain bullets, .300 Magnum with 165-180 grain bullets, or .338 Magnum with a 200 grain bullet, the rifle should be sighted to put the point of impact approximately 2.5 inches above the point of aim at 100 yards. In other words, you should aim exactly at the center of the bulls-eye and the bullets should land about 2.5 inches directly above the center of the bulls-eye. Get it? That maximizes the point blank range of your rifle, eliminating the need to hold over any big game animal from the muzzle out to a distance of about 300 yards (or more) with the cartridges and loads mentioned above. Check the Rifle Trajectory Table for the exact 100 yard point of impact and MPBR for your cartridge and load.
If you are sighting-in a medium range rifle like a .30-30 with 150-170 grain bullets, .300 Savage with 165-180 grain bullets, .30-06 with a 220 grain bullet, .32 Winchester Special with a 170 grain bullet, .338-57 O'Connor with 200-225 grain bullets, .35 Remington with a 200 grain bullet, .358 Winchester with a 200 grain bullet, .416 Rigby with a 400 grain bullet, .444 Marlin with 240-300 grain bullets, or .450 Marlin with a 350 grain bullet, you will want your bullets to hit about 3 inches high with a center hold at 100 yards. This will give you a MPBR of about 200-250 yards, depending on the individual caliber and load. Once again, you will aim at the center of the bull's eye, and adjust the actual point of the bullet's impact to be about 3 inches directly above your point of aim.
Let's say, for example, that your are sighting-in a .270 Winchester rifle using a load that drives a 130 grain bullet at a MV of 3100 fps, and your first 100 yard 3-shot group landed in a 2 inch circle centered 3.5 inches above the center of the target and 1.5 inches to the right. With that load you want the bullets to hit exactly 2.5" above the point of aim (the center of the bull's-eye) at 100 yards, so you need to move the point of impact 1 inch down and 1.5 inches to the left.
For serious sighting-in it is best to adjust the scope in only one direction at a time. Scope adjustments frequently interact with each other (they should not, but in the real world they may); so by changing only one at a time the effect is minimized. Move the elevation adjustment 4 clicks in the "down" direction. That should be 1 inch at 100 yards for the scope in our example.
Now shoot another careful 3-shot group, making sure that the barrel has time to cool between shots. Take your time and do it right. Did the center of the group move so that it is now 2.5 inches over the point of aim? If it did, good enough; if not, you will have to make another elevation adjustment and shoot another 3-shot group. This is where a good scope with precise adjustments really justifies its higher price.
Once the elevation is correct and the center of your group is the necessary 2.5" above the point of aim, go on to the windage adjustment. The rifle in our example is hitting 1.5 inches to the right, so we need to move the center of the group 1.5 inches, or 6 clicks, to the left. Go ahead and make the required adjustment. After the barrel has again cooled to the ambient temperature, fire three more careful shots, always holding on the exact center of the bull's-eye. If all went well, the rifle should now be putting its bullets 2.5 inches directly over the center of the bulls-eye, the point of aim.
If you have the extra ammunition, shoot a final 5-shot group to insure that everything is as it should be. Congratulations, your rifle is now correctly sighted-in.
If all went well you have probably used about a box of cartridges to sight-in your rifle. That's not too bad. I'd stop at the end of that first box and either shoot something else or call it a day and go have a cup of coffee. (Never drink coffee before a range session as it will increase the size of your groups, guaranteed.) You deserve it!
About the Author
Chuck Hawks of Guns and Shooting Online - reproduced by permission.
A Quick Note About Legal Big Game Hunting Rifles in Colorado as Mandated by the Colorado Division of Wildlife
In Colorado a center fire rifle is required and:
- The minimum caliber is .24 (6 mm)
- The rifle must have a minimum 16-inch barrel and be at least 26 inches long
- Semi-automatic rifles are allowed but fully automatic rifles are prohibited
- If semiautomatic, the rifle can hold a maximum of 6 rounds in the magazine and chamber combined
- Hunters must use expanding bullets that weigh a minimum of 70 grains for deer, pronghorn and bear; 85 grains for elk and moose; and have an impact energy rating (at 100 yards.) of 1,000-ft. pounds as rated by the manufacturer
- It is illegal to hunt game birds, small game mammals, or furbearers with a centerfire rifle larger than .23 caliber during the regular rifle deer and rifle elk seasons West of Interstate-25, unless hunters have an unfilled deer or elk license for the season they are hunting. A small game license is required
Good luck and happy hunting from Rocky Mountain Ranches, LTD