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JC10311
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Posted: 5/22/2012 8:45:57 PM
I'm not sure if this is the right place to post this, but I want to let people know about my experience with the Bushnell laser bore sighter.



The problem I have is that the sight-in process is NOT repeatable. Here are the steps I went through.

1. Scope mounted and tightned –– it is not moving.
2. Insert laser bore sighter and shine on wall at 30 yards. I used the instructions and made sure that the adapter was snug in the barrel.
3. Adjust scope so that cross hairs are centered on the red dot.
4. Remove bore sighter and put it back in as above.
5. Check the scope and the dot is 6" right and 3" low of the cross hairs. I did NOT touch the scope adjustment.
6. Remove the laser and repeat one more time. Now the dot is 2" high and 1" left of the cross hairs.

I repeated this test using two other guns with different calibers with similar behavior. I did NOT turn off the laser in between tests or guns. I suspect that the adapters do not engage the rifling the same way each time which throws off the centering just a little. At 30 yards it makes a very noticable difference.

Even with this variability it's good enough to get me on paper at 25 or 50 yards, but it's frustrating to have a tool I don't trust.

Has anyone done a similar test with this bore sighter or the ones that go into the chamber?
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Russ4777
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Posted: 5/22/2012 9:48:28 PM
Those tiny screws on the side of the unit near the end are for aligning the laser to the housing. When the unit is rotated in the bore, your spot should not move or oscillate on the target. Adjust the screws to align it. A new unit should not need this adjustment.
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JC10311
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Posted: 5/22/2012 10:06:16 PM
Originally Posted By Russ4777:
Those tiny screws on the side of the unit near the end are for aligning the laser to the housing. When the unit is rotated in the bore, your spot should not move or oscillate on the target. Adjust the screws to align it. A new unit should not need this adjustment.


I tried that. When I just turn the unit in the bore the dot doesn't move. It only changes position when I remove it entirely and put it back in. It is a brand new unit bought yesterday. The three guns I tried were 7mm Mag, 300 BLK and .308. I know that 300 BLK and .308 are the same bore size, but they have different twist rates. The 7mm mag and .308 have target crowned barrels but the 300 BLK has a Miculeck comp.
The meaning of peace is the absence of opposition to socialism.
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Avidrook
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Posted: 5/22/2012 10:19:53 PM

I tried one of these on two AR's withought sucess (not this brand though). I have used it on other rifles and it got me on paper. That really is all you can expect from it.

With the AR I think the A2 break threw it off. I wasn't even on my targer backer at 25 yds after using the bore sighter.

With a rifle where the body of the sighter touched the crown I had much better results.


JC10311
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Posted: 5/22/2012 10:33:33 PM
The only reason I was expecting more was this paragraph in the instructions:

"Final sighting in must be done at the range. After final sighting in is done you can use your boresighter to record the actual location of your zero relative to the crosshairs. This is [a] handy reference if you wish to verify your zero later."

Not if the dot keeps moving. I'm going to play with the inserts and alignment to see if I can figure out where the variability is coming from –– my technique or the device.
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RandyStacyE
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Posted: 5/22/2012 10:47:04 PM
[Last Edit: 5/22/2012 10:49:24 PM by RandyStacyE]
I have always used Aimshot laser boresights. They have always got me on paper the first shot. Now a days I don't bother using laser boresights. I fire a shot at 50 yards. If I don't hit paper at 50 yards then I simply walk up on the target and fire another shot. I usually hit paper, make adjustments, walk back to 50 yards and fire another shot to confirm. If I'm trying to sight in a magnified optic then I go out to 100 yards and continue to sight it in.

Lasers that are stuck into the end of the barrel are WAY much more likely to be off than a chambered laser. If you have the option to walk up on your target ... you don't need a laser anyway.
frankiebagadonuts
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Posted: 5/23/2012 8:48:19 AM
IMO, laser boresighters are useless except for the cartridge specific ones that fit into the chamber. Just boresight it by placing your rifle (bolt gun) or upper (AR) on a rest and looking through the bore. Aim at a bright target (i.e. orange paster), then adjust sights so they are alos lined up on this target. This method has always got me on paper.
Choncer
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Posted: 5/23/2012 8:54:49 AM
This type of boresight consistently gets me within 3" of bullseye at 50 yards. Used them with everything from .22 to 30-06
JC10311
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Posted: 5/23/2012 9:48:00 AM
Originally Posted By frankiebagadonuts:
IMO, laser boresighters are useless except for the cartridge specific ones that fit into the chamber. Just boresight it by placing your rifle (bolt gun) or upper (AR) on a rest and looking through the bore. Aim at a bright target (i.e. orange paster), then adjust sights so they are alos lined up on this target. This method has always got me on paper.


That's the method I've used for forty years, but I thought I'd try high-tech. The part that really interested me was the possibility of rechecking zero without having to shoot. That doesn't appear to be possible with this laser. I absolutely believe that I would stay within a few inches at 100 yards, so it's just my uber-perfectionist anal-retentive personality at work.
The meaning of peace is the absence of opposition to socialism.
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metroplex
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Posted: 5/23/2012 2:52:12 PM
Mine works fine. Just use the right adapter and make sure the tapered part of the boresighter sits firmly against the crown of your muzzle. That is what aligns the boresighter, the adapter is there to support the bore sighter. I would tighten it slightly while inside the bore and snug it down.
jn3825
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Posted: 5/27/2012 2:30:42 AM
Originally Posted By frankiebagadonuts:
IMO, laser boresighters are useless except for the cartridge specific ones that fit into the chamber. Just boresight it by placing your rifle (bolt gun) or upper (AR) on a rest and looking through the bore. Aim at a bright target (i.e. orange paster), then adjust sights so they are alos lined up on this target. This method has always got me on paper.


+1

I'm all about nifty gadgets but the old school method is the best on this one. Chamber specific may be useful on something you can't look down the bore of something like a 10/22, as long as you aren't trying to use it on a day with any sunlight. Inside maybe if you have a nice long hallway or something. However I am lucky enough that the local surplus store has the military 1000 yard targets. If you can't get on paper with that thing at 50 yards I think there's bigger issues. Google 6920-01-M11-3906. They're great.
JC10311
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Posted: 5/27/2012 10:48:29 AM
[Last Edit: 5/27/2012 10:49:14 AM by JC10311]
I have found the perfect use for this thing. The cat is completely worn out, and my wife is PISSED OFF at me for making the cat climb the drapes.

Seriously, I think that it's about as good for initial sight in as looking through the bore –– it will get you on paper. It is nice not to have to lock the gun down while looking through the bore and back to the scope several times. As fo[r] recehecking zero –– it's useless. For $40 I won't gripe too much.
The meaning of peace is the absence of opposition to socialism.
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scudzuki
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Posted: 5/27/2012 1:31:49 PM
[Last Edit: 5/27/2012 1:34:21 PM by scudzuki]
Originally Posted By Choncer:
This type of boresight consistently gets me within 3" of bullseye at 50 yards. Used them with everything from .22 to 30-06


This is my experience as well.
However, you need access to the crown to make it work.

Joe
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Posted: 5/27/2012 3:47:55 PM
Originally Posted By frankiebagadonuts:
IMO, laser boresighters are useless except for the cartridge specific ones that fit into the chamber. Just boresight it by placing your rifle (bolt gun) or upper (AR) on a rest and looking through the bore. Aim at a bright target (i.e. orange paster), then adjust sights so they are alos lined up on this target. This method has always got me on paper.


This method has never failed me.