Verifying Scopes That Won't Hold Zero

[Joefear7]

So recently I put a new Ballistic Advantage barrel on my AR and I'm getting like 6 MOA at 100 yards. The AR Stoner barrel I replaced it for shot maybe 4 MOA.
I thought at first it was the cheap AR Stoner barrel but now I'm pretty much thinking its the scope that is not holding zero.

I have to put a known good scope and mount on it to verify its the scope, but haven't been able to make it to the range in months.

Whats the best way to test the scope for holding zero without actually putting it on a gun and firing it? I also encounter customers on a daily basis who claim their scopes aren't holding zero and need a better way to verify this as I can't take it to the range.

[Citadelgrad87]

Ive never had the bad luck to have a wandering scope, but afaik, there is no way to verify that a particular scope is holdig zero other than to shoot it.

The recoil is what is making the scope wander, if it is wandering.

Even boresighting is just an approximation and nowere near precise enough to pick up wandering zero.

When you DO shoot, do it from good support with quality ammo and take everything out of the equation other than the scope.

Good luck.

[ja308]

What scope did you use when the gun shot 4 minutes ?
That said I havn't personally witnessed a scope drifting. I have frequently found loose sights and actions that caused erratic shot placement.

I would guess and its only a guess that a consistent 6 minute group vs a consistent 4 minute group would be the barrel you replaced or ammo.

My guess is based on a faulty scope would probably throw the shots off to where you would have no group.

[Scratch705]

a change of grouping after barrel swap? i would say the barrel is the cause. either not enough torque, too much torque, defect or bad bolt to barrel match or it doesn't like the ammo you are shooting.

a lot of other factors besides scope issue.

[MARKFP]

I have had similar issues with scopes over the years and due to a unique issue with one scope in particular discovered the process of lapping the rings. Wheeler makes a kit for doing this, go to video archives and you can see the process. All machine parts are not perfect, and AR rails, base mounting holes and other attachment fixtures are NOT machined perfect. A little here and there and it will drive you nuts. If the rings are not lapped into perfect alignment it will not allow your scope to bed properly on bottom rings, therefore "floating" no matter how tight you secure the cap screws, which if you over tighten can flex the scope tube and "pop" something inside. The floating attitude in mis-aligned rings can allow your scope to move with minimal recoil. I have actually broke scopes mounting in mis-aligned rings. Look at video on Midway about the Wheeler scope mounting kit, which also includes a torque wrench with ratings according to screw size. Not saying this IS your issue, but similar to problems I've had.

[smoothy8500]

I'm generally suspicious of "scope won't hold zero" claims. Almost every problem is ammo/barrel/mount/shooter related. "Scope won't return to zero"? Yes, I'll believe that claim since it's readily provable.

[Black Majik]

Do a box test to see if the scope tracks correctly. It'll see if you're zero is consistent once you get back to your original POA.

But also, make sure your barrel was correctly fitted. Take it to a quality gunsmith to check.

Lastly, run some good quality match ammo through it. Not 55gr plinking ammo. Also make sure the weight matches with the twist of your barrel.

Process of elimination.

Also. What scope are you using? What mount? What Ammo?

[lordmorgul]

Verifying Scopes That Won't Hold Zero

I'm generally suspicious of "scope won't hold zero" claims. Almost every problem is ammo/barrel/mount/shooter related. "Scope won't return to zero"? Yes, I'll believe that claim since it's readily provable.

[baih777]

Sight in at 50 yds
Use a rifle rest.
Use the proper target for sighting in.

https://www.walmart.com/ip/10-Pcs-of-Advanced-Rifle-Sighting-Target-Black-amp-Red-Size-14-x-15/829189845?wmlspartner=wlpa&selectedSellerId=2436&adid=22222222228093473720&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=m&wl3=213888962795&wl4=aud-566049426705:pla-346591494905&wl5=9031044&wl6=&wl7=&wl8=&wl9=pla&wl10=113134515&wl11=online&wl12=829189845&wl13=&veh=sem&gclid=EAIaIQobChMIooLkkpDQ4AIVQRx9Ch1xxQ6EEAQYBCABEgL11vD_BwE

Most likely it's your ammo and barrel.
Since you changed barrels. You need to find the ammo that works with that barrel.
There was most likely nothing wrong with your original barrel. You just need to find the barrel ammo combo that works.

[Joefear7]

Mueller scope
Burris PEPR mount
All kinds of ammo from 55gr factory federal to my 77gr HPBT handloads

[ar15barrels]

So recently I put a new Ballistic Advantage barrel on my AR and I'm getting like 6 MOA at 100 yards. The AR Stoner barrel I replaced it for shot maybe 4 MOA.
I thought at first it was the cheap AR Stoner barrel but now I'm pretty much thinking its the scope that is not holding zero.

I have to put a known good scope and mount on it to verify its the scope, but haven't been able to make it to the range in months.

Whats the best way to test the scope for holding zero without actually putting it on a gun and firing it? I also encounter customers on a daily basis who claim their scopes aren't holding zero and need a better way to verify this as I can't take it to the range.

You need a collimator.
It's a big optical bench device.
You can mount a scope on it and then tap on the sides of the scope and see if the reticle moves around.



That will tell you if you can get the erector to wander, but it won't tell you how the recoil from your specific rifle is effecting the scope.
Only live fire will tell you that.

[langss]

Mueller scope
Burris PEPR mount
All kinds of ammo from 55gr factory federal to my 77gr HPBT handloads

I'm going to go out on a limb here...I have three different rifles with PEPR mounts and three different scope brands, and have not had a problem. I also have used a variety of 55gr..... so I'm going to vote its the scope.

[baih777]

Mueller scope
Burris PEPR mount
All kinds of ammo from 55gr factory federal to my 77gr HPBT handloads

Your 77 gr handloads.
Did you do a ladder test ? Or you loading from the book ?

[ozarkpugs@gmail.com]

If you have a laser or friends who has one mount it to the gun and dial it into the same POA as scope then wiggle on and tap scope . Is the bolt the same bolt you had with the old barrel? Could be a problem with it so if you haven't then swap the bolt. Someone suggested this already ,but shoot a target at 25 yards and then move scope 4 moa r ,the group should move 12" r then go 4 moa up ,then left then down 4" . You should have a square with a group at all for corners and last group should be stacked on the first . The distance is not important as long as its close enough to get a group not pattern and you do the math . As far as barrel torque , unless it is loose enough to move that is not going to be the problem .

Sent from my Moto E (4) using Tapatalk

[smoothy8500]

Almost every problem is ammo/barrel/mount/shooter related.

Mueller scope

Ok, my usual suspects list doesn't include cheap scopes and anything that gets gooey when left in the car...