Gunsmithing Swapped scope mounts, now my elevation tops out. Help!

[Renegade_Red]

Hello all its my first post, wasn't sure if this pertains to Gunsmithing since its just a mount swap but here we go.

I have an AR10 that I swapped out mounts from a Leupold AR mount with no cant to a Griffin Armament cantilever SPRM2 15moa cant. I mounted it myself and torqued all the fastners to spec and made sure the rifle, mount and scope were all level before, during and after the process. I took the rifle to the range today and tried to zero it at 100yds but I topped out my elevation turret and was still in the dirt below the target.

I have factored in that it could be operator error and I botched the mounting, it could also be a broken turret knob but the scope was sighted and functioned just fine in the leupold mount.

I figured I would come to the Hide and ask your opinions and for past knowledge before I went to professional gunsmith and payed a fee for something that I MIGHT be able to fix in house.

Thanks!

 

[_Windrider_]

Hello all its my first post, wasn't sure if this pertains to Gunsmithing since its just a mount swap but here we go.

I have an AR10 that I swapped out mounts from a Leupold AR mount with no cant to a Griffin Armament cantilever SPRM2 15moa cant. I mounted it myself and torqued all the fastners to spec and made sure the rifle, mount and scope were all level before, during and after the process. I took the rifle to the range today and tried to zero it at 100yds but I topped out my elevation turret and was still in the dirt below the target.

I have factored in that it could be operator error and I botched the mounting, it could also be a broken turret knob but the scope was sighted and functioned just fine in the leupold mount.

I figured I would come to the Hide and ask your opinions and for past knowledge before I went to professional gunsmith and payed a fee for something that I MIGHT be able to fix in house.

Thanks!

What scope? Does it have a zero stop?

 

[Jscb1b]

Backwards?

 

[_Windrider_]

Backwards?

. Man I hope not. Trying to give the benefit of doubt on that one but yeah maybe a picture

 

[Winningdog]

From 0 cant to 15 moa cant, should have been shooting high. Is net mount on backwards? Edit. Didn't see the previous post.

 

[pell1203]

Or perhaps not mounted on the rail correctly due to some interference debris or machining mismatch between pic rail on rifle and mount.

Try removing the mount and checking fit on rail. Also double check to confirm the scope rings allow the scope tube to sit all the way to the bottom of the ring.

 

[Bigfatcock]

I bet it's on backwards.

 

[Renegade_Red]

What scope? Does it have a zero stop?

Scope is a Leupold Mk5 3.6-18, it has a zero stop, the Griffin mount has demarcations for the front of the mount so its kind of dummy proof but I understand.

I had the same thoughts that it should be shooting high. @Winningdog

 

[Wannashootit]

Doesn't make sense on a scope with 100 MOA of adjustment.
Were you pretty close to the middle of total adjustment with the original mount?

Some rifles will eat some "up" to get to zero- but it shouldn't be excessive.
You should be able to clearly see a height difference in the rings (lower in the front, duh) to rule out a manufacturing defect.

 

[Renegade_Red]

Doesn't make sense on a scope with 100 MOA of adjustment.
Were you pretty close to the middle of total adjustment with the original mount?

Some rifles will eat some "up" to get to zero- but it shouldn't be excessive.
You should be able to clearly see a height difference in the rings (lower in the front, duh) to rule out a manufacturing defect.

My zero was 10.3 mils from factory zero which was 1 revolution and .3 mils on the elevation turret. On the original i was no where near topping out.
I was trying to find a way to measure the cant displacement but I don't have any dedicated tools. I guess I should take it to a gunsmith to see if he can measure it, that or call Griffin Armament

 

[Renegade_Red]

Are you feeling and hearing a solid click when you adjust elevation?

I am hearing the clicks when I rotate the turret. I'll probably take it to a smith and have him diagnose the issues before I contact any manufacturers.

 

[Wannashootit]

Simple.enough to swap the old mount back if you still have it.
If it were a bolt gun it'd be easy to boresight and not need a range trip.
I'm in the camp that it's the mount. Unlikely the scope went bad (esp a high end Leup) simultaneously with a mount swap...

 

[Renegade_Red]

Simple.enough to swap the old mount back if you still have it.
If it were a bolt gun it'd be easy to boresight and not need a range trip.
I'm in the camp that it's the mount. Unlikely the scope went bad (esp a high end Leup) simultaneously with a mount swap...

Still have the old mount, ill swap it back and see how it zeros. Will have the Griffin mount checked out. Thanks

 

[jetmd]

@Renegade_Red any resolution with this issue?

 

[PDXGS]

To further flog the dead horse....I had a similar issue with a new Leupold Mk8 scope mounted on an old rifle...I couldn't figure out why I was running out of windage...Leuopold techs showed me how to center the reticle using a mirror. This helped me isolate the issue as being with the rifle...Specifically the Rem 700P had the rail mount holes in the receiver drilled about 12degrees off centerline....Yay Remington...
You may want to start by simply centering your reticle and eliminating that as a source of error....Here's a explanation of the mirror method.

How To Optically Center A Scope [May 2019]

If your rifle scope can`t hold zero, reticle is often jumping or your turret adjustments feel weird you need to optically center your scope.

rifleopticsworld.com

 

[Renegade_Red]

@Renegade_Red any resolution with this issue?

Haven't had the chance to head out to the range, bad weather mixed with too much work. Ill strap the old leupold mount back in place and check zero at next range day. If the results are good I'll just return the Griffin mount

 

[chase723]

Also to address another another simple fix. How many mils did you dial when you topped out and couldn’t get on target? You gained back ~4.1 mils with your new mount. You should have had to dial down ~4.1 mils from your previous zero...Prior to rezeroing, did you loosen your set screws and move the turrets to like 5 or 6 mils to let yourself dial back down?