Pennsylvania Firearm Owners Association
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  1. #1
    Join Date
    Jul 2015
    Location
    Lower Macungie Township, Pennsylvania
    (Lehigh County)
    Age
    79
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    Default Boresight Problem

    I have 2 Sightmark boresights, 357/38 and 9mm. They both fit tightly into the chambers of my guns but I get really bad results at the range when I line my sights to them.

    Example. I have a new S&W M&P Bodyguard with the Crimson Trace laser. So I insert the boresight and align the laser to it at 30 ft. I note how I have to line up the gun sights to hit the spot and instead of fenceposting them I have to raise the muzzle so the front sight sits half way above the rear. Fine. I take it to the range, shoot at 30' with and without the laser and am a foot high. If I fencepost the gun sights it shoots good but now the laser spot is a foot low.

    I have a 637 that I put a CT on and get similar results.

    Any comments? Recommendations for a better boresight? I've heard that in-breech lasers aren't really that accurate and that magnetic or in muzzle solutions are better.
    NRA Life Member

  2. #2
    Join Date
    Jul 2013
    Location
    Mohnton, Pennsylvania
    (Berks County)
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    6,145
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    Default Re: Boresight Problem

    I use a collumnator, bore sight. When you look through the scope it puts a grid up. You can tell level with the grid. You center the cross hairs, then shoot. Then put it back in after shooting adjustment and note where the cross hairs are. Now you can always check your zero.

    As for laser sights you have bore axis and laser positions to figure on, you’ll only have one distance where they intersect unless you parallel them and remember the offset.
    The Gun is the Badge of a Free Man

  3. #3
    Join Date
    Oct 2013
    Location
    'burbs, Pennsylvania
    (Bucks County)
    Posts
    646
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    20868185

    Default Re: Boresight Problem

    You donít need a boresight to adjust a laser. Just look through your pistol sights and adjust the laser until it coincides with point of aim at the chosen distance.

  4. #4
    Join Date
    Mar 2016
    Location
    Eastern, Pennsylvania
    Posts
    424
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    12616838

    Default Re: Boresight Problem

    You also have to remember that laser bore sights don't take into account for bullet drop, your sights are zeroed for the most effective range, i know sigs are sighted POA/POI at 25 yards, closer and it'll hit higher, farther it'll hit lower

  5. #5
    Join Date
    Feb 2010
    Location
    Levittown, Pennsylvania
    (Bucks County)
    Posts
    7,768
    Rep Power
    21474853

    Default Re: Boresight Problem

    I think lasers shaped like a cartridge, chambered, and projected through the bore are just intended to get you on paper. Same for the muzzle insert type.

    One way to prove this is to mount the gun rigidly, rotate the laser a bit and re-chamber and note where the dot appears. Pull the laser, rotate say a quarter turn and check again. Do this several times. Does the dot always appear in the same position? If it does, then you could co-witness with the sight(s) fairly reliably. If it draws a circle, it's a get-on-paper device.
    Legislating to prevent people's acts is fantasy

  6. #6
    Join Date
    Apr 2007
    Location
    Pittsburgh, Pennsylvania
    (Allegheny County)
    Posts
    5,362
    Rep Power
    16009908

    Default Re: Boresight Problem

    I concur that boresights and such are to be used only for getting on paper. However, I've never bought or had a pistol that wasn't on paper (paper plate size target) at 7 yards. Most handguns come from the factory pretty much spot on. I just shoot the pistol and if it doesn't hit where I'm aiming, I'll adjust the sights until it does.

    However, you need to take into account that your skills as a shooter may be off, and that you may be adjusting the sights to compensate for a deficiency in your technique. To determine this you need to bench the gun and see where it shoots. You can probably get away with just resting you hands on the bench as opposed to putting the pistol in a shooting vise of some type. Lots of people have tendency to unknowingly push the pistol down when firing due to anticipated recoil which will result in low shots.

    As for setting up a laser sight (your CT), you need to make sure the mechanical sights are hitting where you want first, then adjust the laser until it's sitting on top of the front sight.
    Toujours prÍt

  7. #7
    Join Date
    Feb 2010
    Location
    Levittown, Pennsylvania
    (Bucks County)
    Posts
    7,768
    Rep Power
    21474853

    Default Re: Boresight Problem

    Saw a good example of that at an indoor range. Guy in the booth to my immediate left was shooting a just acquired Sig 226 with a laser attached. I was watching the red dot flying downward just before the gun fired.

    I engaged him in shooting talk, and suggested he do a few dry fires, paying attention to that projected red dot. He was surprised, and thanked me.

    Don't be too quick to look to adjusting sights if POI and POA seem mismatched.

    I have a .45 Colt SAA clone that tends to hit 11 o'clock high (a common occurrence with SAAs, from what I read). I was just about ready to smack the front sight a little to the left, when I finally learned how to shoot the gun.
    Legislating to prevent people's acts is fantasy

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