boresighter problem-- need help

[creophus]

I picked up a relatively cheap Aimshot laser boresighter at the gun show a while back. It's the kind that has the laser in a .223 like shell. It has "arbors" for 308 and 30-06. When trying to use this boresighters per the instructions, I still find that my Leupold Mark 4, mounted via Armalite 1 piece mount is considerably off at 25 yards. About 4" off. At 100 yards, it's not even on the paper.

My idea was to share the Leupold Mark 4 among my AR-10 (LRT-SASS) and AR-15 (Olympic Arms flat top upper & Anvil Arms lower). The laser was supposed to help when changing from one platform to the other, but so far its completely worthless. How can the boresight and scope be so far from alignment on BOTH rifles?? Both rifles have the picatinny flat top rail on top.

[AdamN]

Which way is it off??

[creophus]

The dot always points high and right of the point of impact.

[AdamN]

Is it the same on both rifles?

The laser insert could be out of adjustment

If youre swapping the scope between guns you should be able to get really close by recording where the adjustments are L/R U/D. from gun to gun.

For example, swap from AR10 to AR15 10 clicks up and 8 clicks left (example)

Swap back, 10 clicks down and 8 clicks right

[AdamN]

Also when you put the insert in the chamber do you close the bolt on it??

[creophus]

Is it the same on both rifles?

The laser insert could be out of adjustment

If youre swapping the scope between guns you should be able to get really close by recording where the adjustments are L/R U/D. from gun to gun.

For example, swap from AR10 to AR15 10 clicks up and 8 clicks left (example)

Swap back, 10 clicks down and 8 clicks right That's what I was hoping to do once I get it all set. I wanted to use the laser boresight to make the initial setup easier.

I've tried closing the bolt and not closing the bolt, no significant change in where the laser points. I'm wondering if the laser is bouncing off the bore. I don't know, but it looks round on the target down range.

[AdamN]

The only other explanation I can offer would be that bullets dont travel in a straight line, where as the laser does. Also the scope height above the bore can effect the setting.

The only bore sighters Ive used were the optical type, they pretty much got you on the paper.

Ive also boresighted a gun on the bench, got the gun in a good rest and actually sighted down the bore at a reference point in the distance. Then look thru the scope and they should be pretty close, if not adjust.

[craig110]

That's what I was hoping to do once I get it all set. I wanted to use the laser boresight to make the initial setup easier.

I've tried closing the bolt and not closing the bolt, no significant change in where the laser points. I'm wondering if the laser is bouncing off the bore. I don't know, but it looks round on the target down range.

If the laser unit is out of alignment then the orientation of the bore sighter will impact where the laser is pointing. To test for this, mark the head of the bore sighter, put the gun into a rest or a pile of sandbags to keep it steady, and insert the bore sighter several times with the mark at various clock positions such as noon, 3, 6, and 9. If the dot is moving around on the wall or target, the laser is off center.

[Steve Koski]

Or the wall is crooked.

[craig110]

Or the wall is crooked.

Nah (ignoring that you were likely joking), if the wall was crooked the dot should still remain at the same spot. That is the nice thing about trying this test: As long as the gun is held in place nothing else has to be accurate for it to work. As an aside, of course, the longer the distance between the gun and the wall / target the better for spotting offset errors.

[MakeMineaP99]

I forget Craig is an engineer, can't bluff him. :yesnod:

[Steve Koski]

An enjuneer lawyer? Oh no.

[JLarsson]

Almost as bad as an engineer insurance salesman. :D

[Tailgunner]

I bore sight with a Mark-1 eyeball. For those actions that you can't see straight through, simply add a small mirror in the ation port.
A simple aid to the process is to used a piece of fired brass, with the primer removed. It acts like a peep sight in helping to align your eye to the bore centerline.

[djw]

quiet Tailgunner, you'll put those fancy laser folks out of business!

[Werdna]

Thats a great Tailgunner, I'm gonna have to do that next time.

[Clark]

Get the $60 Leupold magnetic base LED illuminated bore sighter, and never look back.

[creophus]

All good suggestions guys. Thanks. I'll have to try them out once I get more time at the range.