Can anyone explain why a windage adjustment is needed after laser bore sighting a rifle? Elevation is a given, but it is a bit counter intuitive that I would need a 4 moa adjustment in windage after a perfect lineup of the reticle with the laser dot.
Range Report Bore sighting
- Thread starter mdmp5
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The laser is a man made mechanical device with tolerances like every other piece of equipment. The rod may not fit perfectly in the bore and the laser may not point perfectly straight. On top of this, barrel harmonics will cause the POI to shift from the centerline. My 55gr load shoots about 1.5 MOA left of my 77gr load.
They just get you close. I do not own one. I just take the bolt out and look through the bore of the rifle at a target about 100yards away, while holding it still (rear bag) look through the scope and adjust the reticle to match the point of aim of the bore. Its free and easy, if you have a rifle that does not have a higher cheek piece than bore height.
I usually do it that way as well, but I happened to have a laser sighter on me. I was wondering if there was more of a scientific explanation, because it just doesn't make sense that a barrel pointed in one direction would have an impact point away from the center.
D
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Because the scope is not true to the barrel. It is sitting left or right on the horizontal plane. The vertical plane is not as problematic for a laser bore sighter. So, don't line you cross-hair right on the dot. You're only interested in the horizontal line on the dot. Don't confuse the horizontal and vertical lines on the cross-hair with the vertical and horizontal plane the rifle is sitting within.
You can't laser bore sight for windage. The closest thing to that is the Leupold bore sighter. I do like that one. Windage for first shot is anywhere within the circle. But doesn't matter. You're going to look down the bore before the first shot anyway. Then there is the adage that everything should be lined up pretty close with the windage at zero-mark anyway. The Leupold gadget just gets you closer on the windage. The elevation part of the gadget is very good. I've attached a pdf of the scale. When you get it zeroed you use the gadget again and mark on the printout your spot. Using it before you go to the range is nifty because it will reveal if your zero shifted since the last outing. I've had it several years, maybe six or more, and replaced the batteries a few times. It can also be used to visually test if the turret clicks are way off not on the scale or on the scope. Example, the scale may be in half. I've noticed four .25 MOA clicks = 2" on the scale. So, instead of 2" it is really 1". In other words, each line is 1 inch instead of 2 inches. I don't know why Leupold has the scale for 48" total. Also, take your scope height into consideration. Thus, a 1.5" scope height would be between the first and second hash marks for a first shot. My experience it gets you within one adjustment after your first group to zero and call it. Personally, I think it would a good tool for a hunting cold core application zero as well. One cold bore shot, adjust, and call it. It is a diversified little tool.
Remember, its just a gadget. Looking down the bore is free.
You can't laser bore sight for windage. The closest thing to that is the Leupold bore sighter. I do like that one. Windage for first shot is anywhere within the circle. But doesn't matter. You're going to look down the bore before the first shot anyway. Then there is the adage that everything should be lined up pretty close with the windage at zero-mark anyway. The Leupold gadget just gets you closer on the windage. The elevation part of the gadget is very good. I've attached a pdf of the scale. When you get it zeroed you use the gadget again and mark on the printout your spot. Using it before you go to the range is nifty because it will reveal if your zero shifted since the last outing. I've had it several years, maybe six or more, and replaced the batteries a few times. It can also be used to visually test if the turret clicks are way off not on the scale or on the scope. Example, the scale may be in half. I've noticed four .25 MOA clicks = 2" on the scale. So, instead of 2" it is really 1". In other words, each line is 1 inch instead of 2 inches. I don't know why Leupold has the scale for 48" total. Also, take your scope height into consideration. Thus, a 1.5" scope height would be between the first and second hash marks for a first shot. My experience it gets you within one adjustment after your first group to zero and call it. Personally, I think it would a good tool for a hunting cold core application zero as well. One cold bore shot, adjust, and call it. It is a diversified little tool.
Remember, its just a gadget. Looking down the bore is free.
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The main purpose of a laser bore sighter is to get you on paper and not zero your rifle. Once you are on paper you can dial in your zero. Removing the bolt and looking down the bore will achieve the same goal. When using a laser, I adjust the scope from the prone position on a spot approximately 25 yards away and get the crosshairs close. Set your target up about 25 to 30 yards away and send a round to it. Adjust your windage to center and your elevation about 1" below the POI. Remember at 25 yards adjusting your windage and elevations will be 4 times your adjustment at 100 yards. Move the target out to 100 yards and and adjust your windage and elevation to zero. I mostly use my laser bore sighter to keep my chrono from getting lead poisoning 
I usually do look down the bore, just happened to have a laser on me. However, there are some rifles you cannot look down the bore on without crazy disassembly, like my m1a. I need the laser for this one.
"Cannot"? Cannot never did anything. A dental mirror is cheaper than a laser, and can be used for many other things.
It's like others have said, bore sighting is only to get you out of the dirt and onto the paper. You would even have to re-zero if you changed your load components, or brand of ammunition. Different bullets are going to print differently on target, so you know that bore sighting is way less accurate than actual firing the bullet.
If you ever tried to spin the laser in the bore you would see the laser turn with the spin. man made object. Just designed you get you close to paper and out of dirt like others have said.
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My observation from helping many newer shooters sight in their new rifles, is that at least half of those that were bore sighted were 3' to 4' off. I have them take aim at an object, like a can, on the hillside backstop first to get that close. Then go to paper.
If you want too get it out of the dirt, or how ever else you want to put it, then go to walmart and while your standing in line to pay for all the "made in china crap" look around and you see some rally cheap little laser pointers or lights. Take it home and use it to send light down the barrel and line your scope up on the light going down the barrel, and you'll at least be able to get it close enough so that, it won't take a lot of trips back and forth from paper to gun getting it aligned up.
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