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Scope shims: A product for our future?
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I have a Browning .308Win with a Bushnell Banner 6x18 on top. I'm at the top of my vertical adjustment and still hitting about 2" low with 168gr bullets. I like the scope model and just bought a new model Banner in 6x24. In the mounting instructions is a section on installing scope shims. I've never seen this before and am wondering if this is something new that we're apt to see more of in the future. Possibly the scope companies are cutting back on the amount of adjustment available to us. I don't really know for sure, but I am concerned. Anyone else experience this? Best wishes.

Cal - Montreal


Cal Sibley
 
Posts: 1866 | Location: Montreal, Canada | Registered: 01 May 2003Reply With Quote
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I usually cut them out of brass shimstock or thin aluminum (pop cans) depending on what thickness I need or the application.

Scope companies ARE getting cheaper for the most part, but this has been an ongoing problem as every scope/mount combination is somewhat unique.


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Posts: 1700 | Location: Lurking somewhere around SpringTucky Oregon | Registered: 18 January 2005Reply With Quote
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Nearly every problem I have seen lately with gross scope misalignemt has been do to TWO factors NONE of which are the scope Manufacurers fault,really.

First, many factory rifles have misalligned barrels and or scope mount holes or dovetails.It is nearly impossible to get the scope's center in line with the bore under those conditions.

Second as scopes are offered in higher and higher power ranges(due to shooters "needing more power" ,the range of adjustment is LESS.That's why tactical scopes generally have 30mm tubes,to get more adjustment range.

In a 12x or higher 1" tubed scope it is darn tough to offer enough POI adjustment to compoenste for some of the poor machine work on many facorty rifles these days.

Most of the timne,it only takesd a few clicks of W&E to get a scope bore sighted, but when it takes more, it generally is NOT the scope makers fault.
 
Posts: 392 | Registered: 05 October 2003Reply With Quote
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I've got a one piece base on a Steyr BMG 50. Can I shim the rear of this? It's 3.125" between the clamp nuts. And it's got a SA 6-20-56 Mil-dot on it. Any idea how many thou' would be a MOA? I think I'm gonna need to break out the calculator for this!


Collins
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Posts: 2327 | Location: The Sunny South! St. Augustine, FL | Registered: 29 May 2004Reply With Quote
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Shims suck. Mine always liked to work loose, loctite and all, until I epoxy bedded them...just like a stock.

Try the burris signature rings if shims concern you.

Dunno if any of it would hold up to a BMG. I would think that a near perfect fit would be required on that, to distribute the forces better! Good luck!


Believe nothing, no matter where you read it, or who said it, unless it agrees with your own reason and your own common sense.
 
Posts: 1780 | Location: South Texas, U. S. A. | Registered: 22 January 2004Reply With Quote
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quote:
Originally posted by Cal Sibley:
I have a Browning .308Win with a Bushnell Banner 6x18 on top. I'm at the top of my vertical adjustment and still hitting about 2" low with 168gr bullets. I like the scope model and just bought a new model Banner in 6x24. In the mounting instructions is a section on installing scope shims. I've never seen this before and am wondering if this is something new that we're apt to see more of in the future. Possibly the scope companies are cutting back on the amount of adjustment available to us. I don't really know for sure, but I am concerned. Anyone else experience this? Best wishes.

Cal - Montreal


Sounds like something any competent gunsmith could fix.

Can't resist:

Bring it to Dewey, he keeps a 5 lb hammer just for pounding the objective down until it's fixed!

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Bob Shaffer
 
Posts: 1946 | Location: Michigun | Registered: 23 May 2002Reply With Quote
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quote:
Originally posted by sharpsman:
Nearly every problem I have seen lately with gross scope misalignemt has been do to TWO factors NONE of which are the scope Manufacurers fault,really.

First, many factory rifles have misalligned barrels and or scope mount holes or dovetails.It is nearly impossible to get the scope's center in line with the bore under those conditions.

Second as scopes are offered in higher and higher power ranges(due to shooters "needing more power" ,the range of adjustment is LESS.That's why tactical scopes generally have 30mm tubes,to get more adjustment range.

In a 12x or higher 1" tubed scope it is darn tough to offer enough POI adjustment to compoenste for some of the poor machine work on many facorty rifles these days.

Most of the timne,it only takesd a few clicks of W&E to get a scope bore sighted, but when it takes more, it generally is NOT the scope makers fault.


Quit buying Winchesters! jumping
 
Posts: 1610 | Location: Shelby, Ohio | Registered: 03 November 2005Reply With Quote
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quote:
Originally posted by Collins:
I've got a one piece base on a Steyr BMG 50. Can I shim the rear of this? It's 3.125" between the clamp nuts. And it's got a SA 6-20-56 Mil-dot on it. Any idea how many thou' would be a MOA? I think I'm gonna need to break out the calculator for this!


It's a similar triangles problem. Long, skinny similar triangles.

The ratio of a 1" displacement on your target to 100 yards is the same as the ratio of your shim height to your screw spacing.

100 yards is 3600"

1"/3600" = (shim height)/3.125"

or

(shim height) = (3.125/3600)" = 0.000868"

Just under a thousandth.

H. C.
 
Posts: 3691 | Location: West Virginia | Registered: 23 May 2001Reply With Quote
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sounds to me like a new mount is needed. i have seen this happen , but usually from the wrong base or rings.

i will not mount any scope on shims ,when you use shims you change the diameter of your ring which may make your scope egg shaped when tightened. that scope then may be useless on any other setup.
 
Posts: 181 | Location: virginia,usa | Registered: 07 January 2004Reply With Quote
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I am so glad that shims are history. I use Burris Signature rings when an alignment problem occurs.


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Posts: 1297 | Registered: 29 January 2005Reply With Quote
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I have shimmed up bases (just did a JC Higgins FN mauser last week).

The problem with shimming one base of a two piece mounting system, is that the rings are not in line with each other, and will dent a scope when rings are tightened. The problem is eliminated if you use a one piece base, and shim UNDER the base. The rings stay in line.
 
Posts: 304 | Registered: 20 February 2005Reply With Quote
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WHY not machine off the base to get things to fit
instead of raising the one end with shims lower the other by shortning the base


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Posts: 1624 | Location: TEXAS | Registered: 04 June 2005Reply With Quote
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When my GS was alive he used business cards for shims that he'd cut strips off & shellac them letting them dry before inseting them,I watched him do it many times and it worked.
 
Posts: 1116 | Registered: 27 April 2006Reply With Quote
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A buddy of mine had the same problem with a Howa Varminter. As it turns out, the receiver was machined wrong from the factory. You may have a similar problem. As per your question, shims may well be a "product for our future" as long as manufacturers are more concerned about a dollar than they are about making a quality product.


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Posts: 427 | Location: Clarkston, MI | Registered: 06 February 2006Reply With Quote
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