Scope Mounting Problem

[hentown]

Mounted a Zeiss Conquest scope on a friend's Thompson rifle, using medium Burris Zee rings. Everything looks fine, but rifle shoots 8" high at 100 yds, with full down adjustment maxed out.

Can't imagine that scope shooting that far off @ 100 yds. Have ordered Burris Sig rings with .020" insert to see if that will correct problem.

Any other suggestions would be appreciated. I've mounted lots of scopes on lots of different kinds of rifles and never ran into this problem before.

 

[Coltdriver]

If you don't know where the variation is, try reversing the rings first.

If the result is the same, see if you can shim the back ring. Go to a hobby shop and get a piece of .01 thick metal and cut a piece for your back ring.

It is easily possible that the barrel does not align to the top line of your receiver and you are getting a high shot.

 

[rcmodel]

Any chance you already got the 'optional' off-set Z-Ring inserts by mistake?

rc

 

[jmr40]

Never mounted a scope on a Thompson. Any chance the front and rear bases are reversed? On Remington, Winchester and Ruger the rear receiver bridge is lower than the front and uses a thicker base, or taller ring with Rugers. Others, such as Savage are the same.

 

[hentown]

First think I did was reverse the rings. Shoots the same. I have some Signature Zee rings ordered, as I stated in my original post. The current Zee rings aren't Signature rings and don't feature an insert.

Another possibility, I'm afraid, is that somebody might have screwed the scope's internals up by maxing out the elevation adjustment. I've heard of that happening and that, sometimes, running the turret fully through it's range and then back to center will sometimes fix that problem. Suggested that the owner try that, but haven't heard back from him with the results.

 

[Mousegun]

If the result is the same, see if you can shim the back ring. Go to a hobby shop and get a piece of .01 thick metal and cut a piece for your back ring.

Front ring.

 

[Grumulkin]

From having used them a long time ago, I believe some Z-Rings were off center to allow for POI adjustment. I used them for awhile on a 7mm Rem. Mag. and became disatisfied with them so went to Warne steel bases with QD rings and have never looked back.

I have the Warne bases on all my Encore and Contender rifles so can easily move scopes around when I get bored with one barrel and wish to use another for awhile.

All that said, I suspect the problem is with the scope and not with the rings or bases.

 

[jmr40]

First think I did was reverse the rings.

Not the rings, the bases may be reversed.

 

[hentown]

It's a one-piece Weaver base that came with the rifle. I'm pretty sure the Signature Zee rings with the .020" insert in the front ring will solve the problem.

 

[greyling22]

I have a rifle that something is off on. Tried several ring and scope combos before deciding something was just weird. I'm running the signature with shims and it works great now. I forget the exact numbers, but I used the biggest shim on the bottom rear and the next biggest on the top front. It got me within 4 inches at 100 and shoots great now. They are a little ugly, but the work well and as advertised.

 

[jerkface11]

You didn't get a 20 MOA base by mistake did you?