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Bore Sighting
- Thread starter house
- Start date
If you are shooting a bolt action, the first thing I would do is place the rifle on bags and pull the bolt out, sight through the bore, then, without touching the rifle, look through the scope and see if you are on the same continent.
If you are, then the next question is, do you have a way to fix the rifle on the bench? If you do, you can sight (start at fifty yds or maybe even 25) a point and after firing, crank the scope crosshairs to the point of impact. After firing you can reposition the rifle so the scope is back on the aimpoint and carefully adjust the scope crosshairs to the aim point, but the adjustment must be one without moving the rifle. Then progress incrementally down range with the target and fine tune with a spotting scope.
If you don't have a way to fix the rifle, you'll need to know the distance your scope adjustment knobs move the crosshairs at a given distance (say, 1/4 in @ 100 yds, per click or graticule mark), compensate for your firing distance and adjust accordingly. Remember, a 1/4 inch per click at 100 yds is about half that at 50 and twice that at 200. It's not 1/4 inch at all distances. All scopes don't use 1/4 inch at 100 yds either. Find out what yours is. It's usually marked on the adjustment disc. I was surprised once to find a Leupold used 1/2 inch at 100 yds.
Use the trajectory tables usually found in a reloading manual for predicted rise and drop of your weight of bullet, as it moves down range, at your velocity. Move the target down range until you observe a zero at your desired range. repeating adjustments at each new target range, as necessary.
Make double sure the scope-to-mount and mount-to-rifle is snug and you use Locktite or Guntite on the mounting screws. This will save a LOT of grief.
[This message has been edited by sensop (edited March 30, 2000).]
If you are, then the next question is, do you have a way to fix the rifle on the bench? If you do, you can sight (start at fifty yds or maybe even 25) a point and after firing, crank the scope crosshairs to the point of impact. After firing you can reposition the rifle so the scope is back on the aimpoint and carefully adjust the scope crosshairs to the aim point, but the adjustment must be one without moving the rifle. Then progress incrementally down range with the target and fine tune with a spotting scope.
If you don't have a way to fix the rifle, you'll need to know the distance your scope adjustment knobs move the crosshairs at a given distance (say, 1/4 in @ 100 yds, per click or graticule mark), compensate for your firing distance and adjust accordingly. Remember, a 1/4 inch per click at 100 yds is about half that at 50 and twice that at 200. It's not 1/4 inch at all distances. All scopes don't use 1/4 inch at 100 yds either. Find out what yours is. It's usually marked on the adjustment disc. I was surprised once to find a Leupold used 1/2 inch at 100 yds.
Use the trajectory tables usually found in a reloading manual for predicted rise and drop of your weight of bullet, as it moves down range, at your velocity. Move the target down range until you observe a zero at your desired range. repeating adjustments at each new target range, as necessary.
Make double sure the scope-to-mount and mount-to-rifle is snug and you use Locktite or Guntite on the mounting screws. This will save a LOT of grief.
[This message has been edited by sensop (edited March 30, 2000).]
Art Eatman
Staff in Memoriam
No arguments with the above; maybe a bit of re-wording...
I start by trying (and boy, with tri-focals, is it trying!) to get the bore centered on the target at 100 yards. Then, twiddle the scope as mentioned above, until they're generally together. This generally guarantees that you'll hit a sheet of typing paper at 25 yards. I just take a sheet of paper, draw a horizontal line with a pentel, and three vertical lines to give me a "starting point target" with three aiming points.
I zero at 25 yards, since with the .243/.270/.30-'06 class, dead on at 25 is around a couple of inches high at 100--mas o menos. But at least you're then close to where you want to be.
Never forget that it takes four times as many clicks at 25 yards as at 100 yards. Tiresome. I don't shoot groups during the 25-yard phase. Shoot, move the crosshairs, etc. After the first dead-on shot, I KNOW I'm in the paper at 100...
Hope this helps, Art
I start by trying (and boy, with tri-focals, is it trying!) to get the bore centered on the target at 100 yards. Then, twiddle the scope as mentioned above, until they're generally together. This generally guarantees that you'll hit a sheet of typing paper at 25 yards. I just take a sheet of paper, draw a horizontal line with a pentel, and three vertical lines to give me a "starting point target" with three aiming points.
I zero at 25 yards, since with the .243/.270/.30-'06 class, dead on at 25 is around a couple of inches high at 100--mas o menos. But at least you're then close to where you want to be.
Never forget that it takes four times as many clicks at 25 yards as at 100 yards. Tiresome. I don't shoot groups during the 25-yard phase. Shoot, move the crosshairs, etc. After the first dead-on shot, I KNOW I'm in the paper at 100...
Hope this helps, Art
house:
on bore sighting, assuming a scoped, bolt action rifle, try the following, it works if you proceed with care.
1. remove the bolt
2. set rifle up on a rest of sorts, sandbags will do.
3. looking through the bore, move the rifle till you see the aiming point on a target you previously hung, say at 100 yards.
4. without moving the rifle, turn the scope adjustment knobs till the reticule is centered on the aiming point.
5. Fire on target, your shot should hit close to aiming point, perhaps you will even hit it first time, likely not. Fire at least 3 shots, with same hold to see where your group is, respecting aiming point. Adjust as necessary, to hit aiming point.
6. check scope mounting, and guard screws prior to actual shooting.
7. that is about it, this method has always worked for me, lacking a bore sighter, which is an optical device that one inserts into the muzzle.
on bore sighting, assuming a scoped, bolt action rifle, try the following, it works if you proceed with care.
1. remove the bolt
2. set rifle up on a rest of sorts, sandbags will do.
3. looking through the bore, move the rifle till you see the aiming point on a target you previously hung, say at 100 yards.
4. without moving the rifle, turn the scope adjustment knobs till the reticule is centered on the aiming point.
5. Fire on target, your shot should hit close to aiming point, perhaps you will even hit it first time, likely not. Fire at least 3 shots, with same hold to see where your group is, respecting aiming point. Adjust as necessary, to hit aiming point.
6. check scope mounting, and guard screws prior to actual shooting.
7. that is about it, this method has always worked for me, lacking a bore sighter, which is an optical device that one inserts into the muzzle.
Gale McMillan
Member In Memoriam
Set the rifle up on the bags and while you are looking through the bore if you will split the bore with the edge of the target frame you can get a much more accurate sight picture Adjust the cross hair and then move it up to the target top and split the bore horizontally and crank the cross hair to that position . Now move to the target and take a perfect hold and touch it off. Spot the hole and note the number of inches to the place of aim. Adjust the cross hairs to the number of inches remembering most scopes are ¼ inch to the click. After this fire one more shot and note the impact point it should be within an inch so make one more adjustment and shoot the final shot and you are finished