Turning a O moa base into a 20 or 30 moa base ?

[Old Corps 8541]

My club started a new game 200 Yd. RF silhouette match's and I've been given conflicting info. on shimming a base to make it a 20 + moa base.
Which end do I shim , the front or the back ?

thank you

 

[kl3309]

My club started a new game 200 Yd. RF silhouette match's and I've been given conflicting info. on shimming a base to make it a 20 + moa base.
Which end do I shim , the front or the back ?

thank you

Shims under the back end to gain elevation.

 

[Tiger_Shilone]

Shim the rear to give you more elevation/distance.

Better yet, get the right base to begin with and avoid problems with inconsistent precision and accuracy. By shimming, you are wedging parts and introducing stress. Will that stress affect your rifle? Same argument I have against shimming scope ring bases or inside the rings themselves. We have plenty of well made parts now that do the proper job, unlike years past when 20,30,40 or more MOA bases just weren’t available and people had to come up with ad hoc solutions.

 

[DFOOSKING]

How do you know you even need a shimmed rail to shoot 200yds?

What is the rifle/scope?

 

[oldrifleman]

The problem with shimming is that is inconsistent in left right and increase the stress on the mount which will find a way to relieve its self at some point over time shifting your POI. Just get a new base and aim for 30 to 40 MOA total.

 

[Ronws]

I agree that shimming is not the best idea. For all the time and effort, just buy a 20 MOA base. EGW has them cheap and effective. Others make them, too.

You can also get 30s and 40s. Whatever you think you are going to need though I cannot yet imagine you needing anything more than a 20 MOA rail, whether you zero at 100 or 200 yards.

I could be wrong and YMMV.

 

[Topstrap]

Shouldn't need it for only 200 yards. Depends on scope though.

Topstrap

 

[DownhillFromHere]

If OP is only going to 200 yards, 8 mils or 25 MOA of "up" from a 50-yard zero is all that's needed - which pretty much any half-decent scope, let alone a good scope, is going to provide mounted on a flat rail.

Do.Not.Shim. Unless a shim is manufactured with tight tolerance to match the contour of the receiver to which it's mounted, it will either unevenly stress the receiver or fail to hold the optic securely (probably both).

If more elevation is needed for other applications at longer ranges, buy a new pic rail made for the rifle.

 

[whatsupdoc]

If OP is only going to 200 yards, 8 mils or 25 MOA of "up" from a 50-yard zero is all that's needed - which pretty much any half-decent scope, let alone a good scope, is going to provide mounted on a flat rail.

Do.Not.Shim. Unless a shim is manufactured with tight tolerance to match the contour of the receiver to which it's mounted, it will either unevenly stress the receiver or fail to hold the optic securely (probably both).

If more elevation is needed for other applications at longer ranges, buy a new pic rail made for the rifle.

7-8 mils of scope elevation at 200 yards is with a 20 moa rail.

 

[DownhillFromHere]

7-8 mils of scope elevation at 200 yards is with a 20 moa rail.

Sigh. Rifle is zeroed at 50 yards. Or 100. Or whatever. Whether the scope is mounted on a flat rail or 50MOA rail, the zero is 50 yards and elevation is calculated from that zero. The rail angle has nothing whatsoever to do with that elevation - all it does is add its angle to the scope's upper elevation limit.

 

[Rob01]

7-8 mils of scope elevation at 200 yards is with a 20 moa rail.

No. 7-8 mils from zero.

 

[david walter]

Burris Signature XTR rings can have up to 40 MOA of bias through the use of nylon inserts in the rings.

No need to shim at all.

 

[Old Corps 8541]

Thank you ALL, this weapon is my "tree rat" controller , a Volquartson built 10-22 , now wearing a 4 x glass. I do have some older 36 x fixed BR scopes that I'll "O" in the back yard at about 30 ft. and see how high the impact is moved with the Elev. turned all the way up. Then break out the calculator and see what that gives me at 200 yds with Std. Vel. ammo.

 

[6.5SH]

0/20/30/40 MOA options from EGW and fairly inexpensive.

https://egwguns.com/scope-mounts-rings/standard-rifle-scope-mounts/ruger/ruger-10-22/

 

[whatsupdoc]

No. 7-8 mils from zero.

Yes you are correct, and I know this. Brain fart.

 

[Ronws]

0/20/30/40 MOA options from EGW and fairly inexpensive.

https://egwguns.com/scope-mounts-rings/standard-rifle-scope-mounts/ruger/ruger-10-22/

That's where I got my 20 MOA for my 7 PRC. Put it on last night. And yes, I ran my turret down 20 MOA. Just need some range time to get zeroed.

For now, as a hunter, I am going to zero at 100. But if I get into long range targets and steel, I could change my zero to 200 yards.