Home Forums Hunting & Shooting Hunting Optics Shimming scope base?

Long story short, the scope is bottomed out and has no more travel but is still 6" high, which base needs to be shimmed....the front or back. I think back but want confirmation.

Thanks

Shimming the front will make you shoot lower, which is what you want. The rule of thumb is that you will get one-inch of change at 100 yards for each .001" (one thousandths) of shim thickness. This assumes a Remington 700 long action, as I remember.

You should return the scope to optic center (so you have maximum internal adjustment) and shim until you are on target. Then, do the fine stuff from there.

Hope this helps.

Steve

Is it common practice to put shims between scopes and rings? Does this not bend the scope and cause the lenses to no longer be aligned? I used to have ...well just say a very popular brand of rings on my gun and I couldn't get the scope crosshairs to go high enough. I was told to put shims in between the scope and rings; and a fellow camfire guru "E4E" went ballistic on how incorrect that was. He told me to use Burris Signature rings and sent them right to me. Solved my problem.

Thanks Zapper;

It is a Rem 700 and I'll be using Leupold shims to make the adjustment.

tlfw et al,

Well I ain't no guru, but I have the same concern you do. Draw a picture of the setup, maybe exaggerated a bit to show the geometry and the issue will be clear. Has to do with parallels, angles, and the like. Seems to me that when you add shims on either end, the scope will sit in the bottom rings at an angle. On those rare occasions when I still do that sort of thing, I lap the rings, then epoxy bed the scope in them (actually I don't do the scope, I use a "dummy" of 1" drill rod). These days I use Burris Signature rings with the inserts just about exclusively. In fact, I just ordered a set about an hour ago. They work great and avoid a whole lot of hassle.

Paul

Here's a simple illustration of what I mean. Take two square or rectangular blocks and lay a straight board or rod across them like a bridge. Everything should be parallel, and the board or rod will make full contact with the surface of both blocks, as long as they are in the same plane. Now raise one of the blocks. Now the board or rod will contact the blocks only on an edge. Like placing a board on some stairs; it will only contact the stairs on the edge. I don't see why it wouldn't be the same with a pair of scope rings. As long as they are in the same plane, fine. But when you raise or lower either one of them so that the surfaces are parallel but in different planes, the scope is only going to make contact on the edge, setting the stage for a dented tube. If I'm wrong, please show me where.

Paul

Have you thought about using cardboard?????? <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Spike:
I hadda problem like that, and I took to my gunsmith who machined steel bases to the correct heights and angles. It works mighty fine.
Smitty of the North

I bet that fix was a tad bit more than the Signature rings with
the offset insert kit! <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />

There's a very good illustration (exaggerated) what non-aligned
rings can do to a scope on this page:

http://www.burrisoptics.com/rings.html

Sinclair carries a lapping kit for scopes.

DannoBoone:
I don't rightly recall, but I think it was $40 bucks, plus the steel Leupold Silver QRW bases that he had in stock. I hadn't been able to find them, and was shimming with Weaver bases. I was doing a sloppy job, and needed a solution.

I've not tried the Signature rings, but it sounds like a good option, if they make them to fit Weaver Style bases. I like to be able to switch scopes. I have a backup scope for each of my hunting rifles.
Smitty of the North

My gunsmith found a .032" shim I had carefully placed between the scope and the lower ring. He laughed, and told me that I would never hit anything that way. There are standard steel shims already made, to go between the base and the receiver. My experience has been, use only steel, not brass, and place the shim between the base and the receiver. $.50 each.

Denton:
I still have the set of steel shims I had ordered from Sinclair. The problem was that they were smaller than the bases. That left a gap under part of the base, and it looked like $hit. That's why I went to my gunsmith, rather than continue with the shimming.
Smitty of the North

Just purchase a set of Burris Signature Rings that accept the plastic inserts. They sell offset inserts up to .020. These rings also hold better, and won't mar a scope tube. They are also self centering which eliminates the need to lap the rings. They are the only rings I use. billt

I don't mean to be contrary, as what works well for one guy doesn't always work well for another and I have no issue with that.

I had 2-3 sets of Burris Signature rings, and while the inserts were okay, I found the rest of the ring lacking. The cross-slot screw is tiny and easy to strip. They weren't easy to take off and on, the mouting tab that contained the threads for the cross-slot screw was hard to line up. One set of ring's cross-slot screws were too short.

I have had no such issues with Leu QRW and PRW rings, nor my Night Force rings.

My shimming story -

Bought a Rem 700 LVSF (221 Fireball but that doesn't matter).

Bought Leuppie dual dovetail bases and leuppie rings.

Put bases on and installed rings using scope alignment bars.

Scope alignment bars showed the front ring was .018 low.

Measured and verified with Leupold all luppie bases and rings were of the proper dimensions.

Leupold graciously sent a shim for front scope base free. (Thanks Leupold) <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Installed shim under front base, stepped back to admire my work.

It (the shimmed front base) looked crappy sitting up off of the action. <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />

Bought Burris signature rings and just one pair of +.020/-.020 inserts (used the +/- 0 inserts on the rear rings).

Installed Burris rings into the Leuppie bases (sans the shim under the front base). Installed the +.020 insert on the bottom of the front ring and the -.020 insert on the top of the front ring. Used the +/- 0 insert on the rear ring.

Looks good, rifle sighted in really close to the scopes center elevation adustment range.

Happy as a clam now! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

My smith won't use shims under bases and for sure not under the scope.He claimsthere is something wrong with the reciever or the bases if the scope won't zero.Only time I had this problem was on a 700 LA and he threw my shims away.All he said was that he fixed it.

Once I determine how much shim to put under the base I cut a little bitty piece about 1/4" sq. and surround it with Brownells Accra-Glass Gell, dyed black, and fix it so it is cemented to the base, not the rifle. Bases are cheap, rifles aren't. I don't worry about ring alignment if the shim is less than about 2 or 3 thousands. The best don't line up exactly any way, or we wouldn't have scope lapping kits. If you are carefull you will need a magnifieing glass to see your work.

I just went through that problem this week. I found that the bases were not level with each other. I took the bases off and put a one piece on (leupold) problem solved. the two piece bases made for the rem 700 appear to be of poor quality. and are not always the right height. lay a steel ruler across one and see if it is the right height. should be level with each other. I am done with them. it's the secomd time they gave me problem's .. no more for me . one piece bases don't need lapped if you buy good ones. you are wasting your time trying to use cheap jap junk. Hubert