If you put the shim under the front mount, it puts additional space beween the line of sight and the path of the bullet thus moving the impact point down.
You can use metal shims made just for this, I'm sure Brownells would have some, but my gunsmith cut a piece of Oak Tag (heavy, glossy, tan colored paper grade school kids use for art projects) about 5/8 inch by 1 inch with a hole in the middle for the mounting screws to pass through. It was installed 29 years ago, and I've never had a problem to date.
One of the slickest scope mounting systems these days are the Burris Signature rings with the polymer inserts. You can get a eccentric kit and adust for gross windage and elevation with the inserts and then fine tune with the scopes internal adjustments. They come in zee ring configuration to fit weaver type bases or in the leupold,burris,redfield type turn in rings as well.
With this system you can acheive the same results as shiming your scope base with out putting any stress on the scope tube. J Sanders
I needed to shim a scope once and got some scraps of brass shim-stock from a local motor rewinder for free [it was a one-piece scope mount so i didn't have to worry about tube stress too much] that seemed to work great.
After messing around with all kinds of material for shims under scope bases, I followed Bob Brownell's suggestion. Use pieces of the metal tape that rolls up into the case. It's somewhat soft, cuts well with metal snippers, and is easy to drill for scope screws.
Best Regards, James
In times past, when I've needed to shim a scope, strips cut from aluminum beverage cans worked nicely. They are easily cut with scissors, and aren't affected by atmospheric changes. A readily available source and the price is right! :smile:
By-the-way, I've moved this thread to the gunsmithing forum so it won't get lost in the shuffle!
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