Boresighting

Discussion in 'Long Range Scopes and Other Optics' started by swpc629, Dec 22, 2013.

  1. swpc629

    swpc629 Well-Known Member

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    I have attempted to boresight 2 scopes on 2 different guns with 2 different laser boresighters. Both scopes run out of movement before either will come up enough to center on the reticle. I have tried both scopes on both guns with the same result. One boresighter is a LaserLyte that goes in the muzzle and the other is an AimShot that goes in the chamber. Can some one please give me some input what the problem may be?
     
  2. bruce_ventura

    bruce_ventura Well-Known Member

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    How far from the muzzle was the target that you're sighting with the the laser and scope?
     

  3. swpc629

    swpc629 Well-Known Member

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    I tried it at 25 ft. to 75ft.
     
  4. bruce_ventura

    bruce_ventura Well-Known Member

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    Sighting in a scope at such short distances is always inaccurate. You could easily have a problem zeroing this way at 25 ft, where the laser is too low by about 19 MOA. At 75 ft the laser is too low by about 5 MOA. That's assuming you ultimately want a 100 yd zero.

    The Laserlyte boresighter has molded plastic arbors that flex when inserted into the bore, allowing the laser to shift as much as 10 MOA from boresight. If the plastic arbor is damaged, the error could be as much as 20 MOA. Try rotating inserting the boresighter rotated 180 degrees. Does the laser spot move a lot? The cartridge type lasers are not much better. When using them it's a good idea to see if the laser is exiting he muzzle in the center of the bore.

    So, you could have ~15 MOA of bore sight error combined with 5 MOA due sighting at 75 ft. If the barrel is installed crooked by even 10 MOA (quite common) in the wrong direction, the scope may not have enough adjustment range.

    I recommend that you check your laser tools to make sure they are accurately indicating the bore axis. Then sight a point about 5 MOA (1.75 inch) higher than the laser spot when sighting at 75 ft.
     
  5. osoh

    osoh Well-Known Member

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    Are your rifles bolt actions? If they are,

    Just for the heck of it, take the bolt out and hang a shiny pie plate or something up a 100 yards out, now that the bolt is out glance down through the barrel from the back of course, and see if you can see your shinny target.
    If you can then get something to stabilize the rifle a little be it sand bags or a gun vise in order to hold your gun solid then try to look through and get the shiny target centered in your view again looking through the barrel. Once centered have another person adjust the turrets until the cross hairs are on your shinny target. Glance back and forth to see if both look spot on. If this is the case you will end up within inches of a perfect shot at 100 yards (if that’s where you hung your shinny target)
    After a while you will be able to do this real fast aiming at a sign, pine branch, target face whatever that you have out about 100 yards to get your scope close for sighting in at 100 for zero.
    No gadgets and fast plus it’s just better knowing you did it yourself.

    Cheers
    oneshot.onehit
     
  6. J E Custom

    J E Custom Well-Known Member

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    +1

    I use a 6 or 8'' black bulls eye pistol target the same way .

    I am normally within 3 or 4 inches the first shot. and by aiming the scope at the same aim point and without moving the rifle , I move the cross hairs to the first bullet hole and I am on. (Two Shots).

    J E CUSTOM
     
  7. bruce_ventura

    bruce_ventura Well-Known Member

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    I agree. I think laser boresighters are just a gimmick. Sighting down the barrel, if your rifle allows it, is actually just as convenient. The best use for a laser boresighter is to tease cats.

    When I'm running scope clinics at the range, I use a boresight collimator for convenience, but it's no more accurate than the method described above. A boresight collimator has a dozen uses, other than zeroing sights.

    Also be aware that barrel vibration can throw shots away from boresight. Aiming errors of 4-6" are common, but I've seen 10" or more, causing shots to miss paper at 100 yds. Barrel vibration is especially bad in lightweight factory barrels on magnum rifles. It's a good idea to fire your first shot at 50 yds to make sure it's on paper.
     
  8. lloydsmale

    lloydsmale Well-Known Member

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    put your bore sighter on a gun thats allready known to be sighted in and see where the lazer hits at the range your using it at and then use that spot to adjust the new gun too. It isnt exact as how high your scope is varys from gun to gun but it should be close.
     
  9. cdherman

    cdherman Well-Known Member

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    I have used the following process with success for years:

    Do this at night. Best of all is a bright light in the distance from your bedroom, where you can aim at the light from a pile of pillows.

    Pull the bolt and bore sight on the light in the distance. It can be a street light, a bright star. Whatever, but it needs to be bright enough that you can see in through the bore, and distant.

    Now start clicking.

    Play with the elevation first.

    Then, if you have Leupold or Burris style bases, where there are two screws in the rear mount, I like to center the scope right to left (count clicks from max right to max left, then center), and initially center the scope with the mount screws. IMHO, this is a good reason to avoid weaver/picatinny bases, as you cannot do this.

    Using this process, I can paper the first shot at 50 or even 100 yards with regularity....