What is the correct way to shim this scope?

G

gc4895

Guest
I will admit to being an iron sight shooter and I know next to nothing about scopes and scope mounting.

I currently have an Anschuts 1807 mounted in an Anschutz prone stock. I have mounted a Leupold 6.5-20x scope on it. I use this prone to work on my prone position since the scope magnifies any movement.

My problem is that I am out of scope UP udjustment to get my bullets centered on a 100 yard target. I am maxed out of UP adjustment and I just make the bottom of the 7 ring on the NRA 100 yard target.

I have a custom made weaver mount in the dovetail of the top of the 1807. This mount has allowed me to use 2 Leupold rings with the quick removal to mount the scope. I guess that this custom mount is flat to the receiver (rather than having any negative tilt) and as a consequence I run out of UP adjustment. I am at about the +2.5 point on the UP adjustment when bore sighting the rifle to the scope.

OK, again, I don't know squat about scopes. I have 25 years of iron sights and 20 minutes of scope shooting in my background.

May I insert a metal shim into the bottom of the rear scope ring? I am guessing I need about 20thou of thickness. I would add this shim to the bottom of the ring, then tighten each ring carefully to minimize the stress on the scope tube. I am thinking I need a shim so that the width of the shim is about equal to the width of the scope ring. Obviously, I'm not shooting a magnum here so I don't need to crank down on the scope rings for tightening them.

I really would appreciate any constructive thoughts here. I'm just trying to get on target at 100 yards.
 
You shim the rear base in the direction you wish your point of impact to travel.

Do not shim inside rings. Rings are made to an exact diameter to fit the scope tube. Placing a shim inside the ring reduces the diameter and when the scope tube is forced into this fit, will crush slightly. It may or may not damage the scope but it is NOT the way to shim for desired elevation.
 
After you shim the rear ring, it will be out of alignment with the front ring by .020 and you will bend the scope tube. Always lap the rings after you shim them.
 
Burris rings

Burris makes a set of Signature Rings that use offset inserts that allow you to adjust for these type on allignment problems.
 
Scope "angle"

Ditto on the Burris Signature Zee rings, for the Weaver base mount. Just bought another set today, the only kind I have bought for the past 6 yrs. With the off-set ring inserts: +.020" top front and -.020" bottom front and +.020" bottom rear and -.020" top rear, you will have all the "up" adjustment you could possibly need. If too much, put a pair of "zeros" in the front or rear ring.
 
Either shim the rear base OR go with the Burris inserts - you won't go wrong with the Burris option!:)
 
Insert sets

Burris sells a Gunsmith set of inserts for 1 in scopes it comes with 0.+-.005, +-.010, +-.020. enough to do 4 or 5 scopes with each size. I bought a set 6-7 years ago and still haven't used them all . I wish they would do the same for the 30mm size rings.......BTW the 1 in set cost about 25-30bucks when I paid for them.It's nice to be able to tune your scope with the .005s an .010s .With the insert sets you have a +40 to -40 adjustment range in .005 increments thats 80 Inches total.
 
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