Adjusting a scope rail

tenmetre · Nov 26, 2022

I have a scope that I want to use on a rifle (AR15) but the snag is it needs lifting at the rear to get it on centre. Unfortunately, because it is an AR 15 upper I cannot just substitute a 20 MOA scope rail so was looking at picatinny/picatinny adapters, there isn't one I can see that has adjustment. Does anyone have any suggestions? The rifle is shooting too high and I need to depress the elevation, just to compound the issue I am shooting 300 AAC BLK out of it so not a flat shooter.

Scottl · Nov 26, 2022

Do you have a milling machine?

If so buy 2 adapters, mill opposite faces of both with one on a taper and fasten them together with screws and Loctite after lapping the milled surfaces for a tight fit.

For the man with machine tools there are always options unavailable to the masses.

deltaenterprizes · Nov 26, 2022

I think that Leupold makes inserts that go inside the rings to adjust for that problem.

Mr.Smith · Nov 26, 2022

I'm probably missing something, but if the rifle is shooting too high, doesn't the rear of the scope need to move down?

Thank you,
Mr.Smith

tenmetre · Nov 26, 2022

Mr.Smith said:
I'm probably missing something, but if the rifle is shooting too high, doesn't the rear of the scope need to move down?

Thank you,
Mr.Smith

Irrespective one end or the other is too high so do you have a solution or just a throwaway comment?

tenmetre · Nov 26, 2022

Scottl said:
Do you have a milling machine?

If so buy 2 adapters, mill opposite faces of both with one on a taper and fasten them together with screws and Loctite after lapping the milled surfaces for a tight fit.

For the man with machine tools there are always options unavailable to the masses.

That could work (I have a Mill or two). AND I have a couple adapters, I will give it a try and report back.

Mr.Smith · Nov 26, 2022

tenmetre said:
Irrespective one end or the other is too high so do you have a solution or just a throwaway comment?

You're correct, of course. However, I will stand by my throwaway comment and leave the problem solving to you.

Thank you,
Mr.Smith

triumph406 · Nov 26, 2022

tenmetre said:
Irrespective one end or the other is too high so do you have a solution or just a throwaway comment?

Don't get your panties in a twist McFly

MilGunsmith · Nov 28, 2022

Burris makes the rings with an adjustable insert in them, unless Leopold has started making them also.

DrHook · Nov 28, 2022

If you have a scope which will not adjust far enough to zero an AR, I would try a different scope before I would machine anything special. The math doesn't work out there, from my (limited) experience. I had a Burris once with a factory issue which prevented it from adjusting far enough in the other direction. Even with the Burris offset rings.

akajun · Nov 28, 2022

Ive never seen a 300blk that shot high at 100 yds especially with subsonics. Id say lets go back and check you setup.
First is the scope rings/ base. If your using rings, make sure they are the same brand and same height. I know it sounds silly but Ive seen mismatches cause this more than you think. If the rings are the same make sure they sit flat on the rail, no burs and the keyway is in the slot.
If your using a one piece mount, make sure its not one of the 10 or 20 moa mounts for long range shooting.

If all that checks out make sure your barrel is installed properly and the shoulder on the barrel extension is flush against the face of the upper receiver tenon .

If none of this works then your options are to buy the rings from burris or leaupold above, or buy a 10 or 20 moa rail from White Oak, install it facing backwards, and use low or extra low rings.

FredC · Nov 28, 2022

akajun said:
If none of this works then your options are to buy the rings from burris or leaupold above, or buy a 10 or 20 moa rail from White Oak, install it facing backwards, and use low or extra low rings.

I like these 2 options, rather than shimming a rail and bending it which may cause stress on the scope tube as well. I put a cheap thermal scope on a 45/70 single shot and the cross hairs were way off center when finally zeroed. I wanted the cross hairs closer to center of the sight picture and Burris rings were the answer.

michiganbuck · Nov 28, 2022

I would bore sight to get the shim or grind near right, and in the right direction before altering anything, but guess you can't bore-sight an AR...darn.
A laser bullet might be good.

Wow 30$ bucks

Sightmark 300 AAC Blackout 7.62x35mm Premium Red Laser Rifle Bore Sight SM39043 | eBay

Find many great new & used options and get the best deals for Sightmark 300 AAC Blackout 7.62x35mm Premium Red Laser Rifle Bore Sight SM39043 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

michiganbuck · Nov 28, 2022

OT: a deer hunt story:
Saturday ( 11-26) I shot a nice 8Pt white tail, 180 lbs on the hoof with a 30-06/150gr at 135 yards with my trajectory set zero @ I50 yards hitting the buck within 1/4" of the sighting.
At the deer location, I found one hoof mark that looked long in the snow and a little hair. Luckily there was enough snow to distinguish that track from other deer.
Following about 200 feet to the first drop of blood...and an increasing blood dropping to the dead deer in another 50 feet or so.
I have been told that a bullet can suck fat into the shot hole and plug it shut for a time if you miss the heart... This was the second time this has happened to me..I use the 30-06 98 Mauser over my 243 just to get a decent blood trail...and the blood trail did not happen.
'No blood trail", so almost impossible to follow the shot deer.
Likely a lot of dead deer are lost because of this..

Scottl · Nov 28, 2022

michiganbuck said:
I would bore sight to get the shim or grind near right, and in the right direction before altering anything, but guess you can't bore-sight an AR...darn.
A laser bullet might be good.

Actually you can bore sight an AR by breaking it open. You won't get a cheek weld for a scope but you can use other methods to at least see where the top of the rail lies in relation to the bore. Possibly with great care you could clamp the upper receiver in position and carefully close the lower without disturbing the bore position.

GGaskill · Nov 29, 2022

If I were bore sighting an AR, I would remove the hinge pin and separate upper from lower. Clamp the hand guard in a vise (works best with a parallel sided hand guard) and aim the bore at a distant target, then adjust sights to bear on the target. The lower has no parts that act in this play.

NewGunPlumber · Nov 30, 2022

MilGunsmith said:
Burris makes the rings with an adjustable insert in them, unless Leopold has started making them also.

Burris signature z rings with offset inserts. It's the easy way

mac1911 · Dec 3, 2022

tenmetre said:
I have a scope that I want to use on a rifle (AR15) but the snag is it needs lifting at the rear to get it on centre. Unfortunately, because it is an AR 15 upper I cannot just substitute a 20 MOA scope rail so was looking at picatinny/picatinny adapters, there isn't one I can see that has adjustment. Does anyone have any suggestions? The rifle is shooting too high and I need to depress the elevation, just to compound the issue I am shooting 300 AAC BLK out of it so not a flat shooter.

Is your end goal to have the scope turrets in the middle of their range and still be zeroed at 100 yards?

Few Questions how high is it impacting and are you out of adjustment on the scope?
1. Double check your scope mount.
A. Rings can be different heights depending on application
B. Rails , I have received off set rails 20 moa in a 0 moa package.
C. How is the scope mounted to the upper. Are the rails machined into the upper or are the held on with XYZ mounting system.

How much your off and a picture of your set up.
Just for info
The scope is essentially the front sight so it moves opposite for correction of impact Your impacts are high you need to raise the crosshair to bring impact down. So Raising the front ring or scope with shims , The Burris system works great.

Details on the scope , mount and rail it sits on

mac1911 · Dec 3, 2022

If your looking for a quick solution to the potential problem

https://heritage-arms.com/product-category/gun-parts/cold-shot-llc-adjustable-scope-bases/

mac1911 · Dec 3, 2022

GGaskill said:
If I were bore sighting an AR, I would remove the hinge pin and separate upper from lower. Clamp the hand guard in a vise (works best with a parallel sided hand guard) and aim the bore at a distant target, then adjust sights to bear on the target. The lower has no parts that act in this play.

Bore sight gets you on paper quickly then you just take a shot , hold platform steady and adjust cross hairs to the impact.

Adjusting a scope rail

Plastic

Diamond

Stainless

Aluminum

Plastic

Plastic

Aluminum

Titanium

Stainless

Hot Rolled

Hot Rolled

Titanium

Diamond

Diamond

Diamond

Titanium

Aluminum

Aluminum

Aluminum

Aluminum

Similar threads