Scope mount shim question

[WheelgunConvert]

I’m using a bore laser to adjust a new scope and have the crosshairs still 4” above the dot and have gone to the end of the adjustment range. Is it proper to add a 10-15 thousandth shim under the rear mount to get back into the adjustment range?

Thank You!
Bevan

[lefty o]

really not adviseable to shim a 2 piece mount. better solution is to use burris signature series rings where you can utilize offset inserts to beter align the scope to the bore.

[WheelgunConvert]

Can you point me to part # please?

I usually shop Brownells

[redhawk0]

https://www.brownells.com/optics-mounting/rings-mounts-amp-bases/scope-rings/signature-zee-rings-prod57094.aspx?avs%7cManufacturer_1=BURRIS

https://www.brownells.com/optics-mounting/optic-accessories/scope-ring-inserts/signature-***-align-offset-inserts-prod26144.aspx?avs%7cManufacturer_1=BURRIS

I use them too...they are awesome rings.

redhawk

[MyFlatline]

I use either a thin piece of packing plastic or dense tape. Have not had any problems keeping zero. You might also try lapping the rings as there could be a high spot.

[NSB]

If you can use a one piece base mount, just get a 20moa base and that will drop you down enough to take care of the problem. Generally, one piece bases work better anyway. They keep the rings on one plane.

[WheelgunConvert]

Thank You again for the guidance.

Bevan

[GBertolet]

According to my chart a .005 shim will give you 5" at 100 yards. You can extrapolate for other distances. Whatever route you decide to go, don't have your scope elevation set at the end, or near end of it's travel, at your final zero. The internal erector tube, will bounce around, due to uneven spring tension, and you will have a wandering zero, if you do. I learned this the hard way. As previously suggested, if you shim too much on a 2 piece mount, the rings will be at too much of a different height, and you could crease or dent your scope tube. I put a wrap of teflon tape around the tube inside the rings. This protects the scope tube, and provides extra slip resistance.

[NyFirefighter357]

I put a wrap of teflon tape around the tube inside the rings. This protects the scope tube, and provides extra slip resistance.

I wouldn't use Teflon tape on a scope....."PTFE has one of the lowest coefficients of friction of any solid. PTFE is used as a non-stick coating for pans. Where used as a lubricant, PTFE reduces friction, wear, and energy consumption of machinery."

[country gent]

On some actions there is a difference in front and rear blocks you might try switching them front to back and see if that helps.. One thing I do do when I have to shim a block is icut the shim rough up the base and shim ( a dowel the same as the action is a big help here) and epoxy the shim to the bottom of the base. clamping it while it cures. I then spot the holes thru the base and clean up burrs and edges. Another thing to check when shimming bases is the ring alignment after its set-to height.

[LAGS]

What was the distance you were using the Bore Sighter?

[GBertolet]

Teflon tape does work. When it is compressed by the rings it grips well. Doesn't mark the scope either. I learned this from a gunsmith. I do this to all my scoped rifles. Never had a scope move.

[WheelgunConvert]

What was the distance you were using the Bore Sighter?
20 yards
I was trying for 1.25 above the dot, but not at the end of the adjustment range.

[WheelgunConvert]

I ordered a set of the Burris rings and offset bushings. Thanks for the input all.

I did try swapping front to back and it did take up some of the difference, but not nearly enough.

[toallmy]

I ordered a set of the Burris rings and offset bushings. Thanks for the input all.

I did try swapping front to back and it did take up some of the difference, but not nearly enough.

Let us know how the rings work out for you if you have time , in a couple weeks I'm going to be working on a very similar problem .

[LAGS]

I sometimes have to shim one base of two piece mounts, and then Lap the rings to line up the two bases so they don't bind on the scope.
I also make sure that the scope is at Center Adjustment to the Scope Tube and leave it there until I get the bases and scope to the point I want the crosshairs to be with the laser,
.
I check all scopes that I mount for Center Adjustment on V Blocks, Not just by counting clicks or numbers of rotation and dividing by 2
By doing it that way, the crosshairs are centered to the Tube of the scope.
A new scope right out of the box is set to Center of Tube, not set to center of dial adjustments.

By doing it that way, It is a lot easier to swap out to another Scope, because the tube to center adjustment of the crosshairs will be the same on both scopes, center of the Tube
All you need to do is the Fine adjustments.