I just lapped and mounted my scope and it is hitting about 10" high with the ajustment turret bottomed out. How much does .001 shim give at a 100 yds?

Regards,
JASON

Jason,

Your 0.001" shim should move the bullet approximately 1" at 100 yards, depending on ring spacing. If you need to move 10 inches, plus have some adjustment available, you probably need about 0.020". This would be a piece of cake with Burris Signature ring offset inserts - you might want to consider them.

Regards, Bill

Signature Rings from Burris with the Insert Kit. Particularly if using 2 piece bases. Sure beats putting a 0.020 bend in your scope

Wally

Bill - thanks for the help.

JASON

Jason,

You're welcome! Wally brings up another good point - if you have a one-piece base, put the shim(s) the under the front of the base. If two piece, I have put a shim between the ring and the scope, but don't like to. If that is what you have to do though, consider "bedding" the bottom half of both rings (if split horizontally), the top halves generally tilt with the scope.

Good luck with it,

Bill

I'm curious as to what the cause of your problem is/was.

What model gun was this and whose rings did you use?

Sounds like you either got the wrong rings for the gun or there was some mistake by the ring maker OR perhaps you overlapped the rings.

And Bill M: couldn't shimming even a one piece base potentially cause the rings to misalign? Seems to me it could. Of course, the desired end result is two rings properly aligned with each other and in relation to the bore however you get there!

[ 09-05-2003, 21:49: Message edited by: sonofagun ]

Flora66,

Something sounds out of whack. If you were to bring this to me, here is where I would look for possible problems.

First thing I would do would be to look at all the obvious things that can cause the gun to shoot too high. For instance, contact between the stock and bottom of the barrel can cause groups to print high. Heavy pressure can cause bullets to fly pretty high so I would look there first to see if something were out of whack.

The next thing I would do would be to perform a quick alignment check of the rings. A quick check can be done by removing the scope ring caps one at a time. Remove the rear cap first and look to see if the scope moves up off the rear cradle. Reattach the rear cap and remove the front cap and see what happens there. If the scope stays put when either ring is removed then vertical alignment is probably fine.

If both of these areas prove good, then I would concentrate on the base itself. You may have to raise the front of the base to correct the mounting problem. I'm not big on using shims as a permanent solution to a problem. However it is a lot less expensive and less involved than what I would personally recommend. And if it's handled right, then I suppose it would provide some relief.

Unless you have access to several bases from which you can measure and try, and unless you are willing to pay a gunsmith to machine the bases to correct a verticle missalignment, then you will have to shim the base.

When you shim the base, regardless whether it is a 1pc, or a 2pc base, you will most likely screw up the alignment of the rings. The solution then would be to shim the base first, and then ream and lap the rings to keep them on the same plane and to avoid placing a bind on the scope.

The slightest bind can throw a perfectly good scope out of whack and cause rounds fly in any direction.

Good luck,

Malm

I'm curious as to what the cause of your problem is/was.

What model gun was this and whose rings did you use?

Sounds like you either got the wrong rings for the gun or there was some mistake by the ring maker OR perhaps you overlapped the rings.

And Bill M: couldn't shimming even a one piece base potentially cause the rings to misalign? Seems to me it could. Of course, the desired end result is two rings properly aligned with each other and in relation to the bore however you get there!

My setup is a 700 SA, IOR HD 2 piece bases, Leupold PRW low rings, to mount a Zeiss conquest 3-9. IOR says the bases are std 0moa but the outcome showed somewhere around 20moa.

JASON

FLORA66,

Like Paul Harvey say's, "And now for the rest of the story".

Based on this information, let me revise my previous post. The first thing I would do, would be to lay a straightedge across both front and rear base and make sure that the straightedge and the receiver are parallel. You will be able to see a 20 minute rake. If the base is not parallel, then you will need to start with one that is...

Good luck,

Malm

Let's start from scratch. double check that the rings have not beem switched, front to back etc.
When I have to shim rings that have already been lapped, I mount the rings to the scope, to maintain alignment, then put the selected shims under the base along with some J B Weld or epoxy to keep the proper angle that the shims have provided. (leave the base screws loose, or if you can not get to them do not forget to align the holes) You do not want to tighten the screws untill the epoxy hardens.
Thinking back I have only done this on one piece bases, but I am sure that you can adapt it in some way to fit your problem. Bernie

I believe I was assuming if you START with a one piece base which fits the receiver PERFECTLY (zero stress on base and receiver when tightened down without any shims)and PERFECTLY aligns the rings, and then shim either front or rear of the base, you WILL introduce stress and misalign the rings. Again, the desired end results are rings perfectly aligned with each other and in correct relation to the bore and with zero stress on any mount components.

As I understand it, one piece bases are less desirable because of their inherent alignment and fit problems.

Think about it - scopes are manufactured to millionth of an inch tolerances and then mounted with .001" - .01" allowances - !

In any case, have we figured out the cause of the original poster's problem yet?

[ 09-10-2003, 04:32: Message edited by: sonofagun ]

sonofagun,

I am not disagreeing with you, but if you're going to shim, you have to put it somewhere. I'd rather put the shim under one end of a one-piece base than between the ring and the scope tube. If you bed/shim it as described above, I'd be surprised if you could measure the change (with "common" inspection equipment). If you shim one of a two-piece base setup, I'd about guarantee that the rings wouldn't line up. And I am not aware of any ring/base combinations that readily allow you to shim between the base and the ring (still probably wouldn't line up).

The best would be to check out everything that Malm suggested, and if the mount absolutely requires canting, re-machine the bottom of the one piece base to match the receiver, at the desired angle. Or use Burris signature rings & offset inserts - still the preferred method in my mind.

Thank you, Malm - that is the bottom line!

Regards, Bill