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Shimming rear base

 
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  #8  
Old 06-20-2002, 01:35 AM
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Join Date: Jul 2001
Location: San Antonio, Texas
Posts: 244
Re: Shimming rear base

Well I'm not quite sure what you mean by the placement of crosshairs in the tube. It really shouldn't matter where they are. The placement of the scope in the rings more toward the front or the back has no effect, the distance of the crosshairs from any point should remain constant. Until you make adjustments, but then it would still remain constant from it's new position. the plane on which the crosshairs sits will be canted forward when shims are used but the position of the plane inside the scope will remain the same.

it's late and I'm tired, not sure if i'm making any sence so I'm gone.
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  #9  
Old 06-20-2002, 08:15 AM
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Location: Pennsylvania
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Re: Shimming rear base

TX

On another note.

With the Unertl or B&L external adjustment scopes, the length of the base was/is a direct reflection to the click adjustment valuations.
A 7.25" base spacing gave 1/4 Min clicks. At 12" it gave 1/8 Min clicks evaluations. The base spacing is a direct reflection of the click valuations in these scopes.

Still use them at 1/4 min spacing.

I have also found that with a .020" tapored base or the Burrus inserts that are .020" will give me 20" height difference at 100 yards or 80 1/4 Min extra usable clicks.
.001" rear height addition has always worked out to 1" at 100 yards for me.

Later
DC

[ 06-20-2002: Message edited by: Darryl Cassel ]
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  #10  
Old 06-20-2002, 08:21 PM
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Join Date: Mar 2002
Location: Prince George British Columbia
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Re: Shimming rear base

The elevation figure for 3"ring spacing makes some sense. Say, .020 for every 3" between the scope and the target. Wouldnt the length of the scope play a part in that also. Near as I can figure, raising the rear base .020 wouldnt have as great an effect on a scope that sticks out 4" past the rings as one that sticks out 8". Doesthis make sense to you guys or are the 70's catching up with me?
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  #11  
Old 06-20-2002, 08:37 PM
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Re: Shimming rear base

MH

It's not the length of the scope (a Unertl is a good example) it's the length of the base and where the rings attach to that base that holds the scope, that is the important factor.

Back to the original question, if you can get 120 1/4 Min clicks (30MOA) from your scope, your 30/06 should make the 1000 yard trip.
.025" to .030" tapored one piece base (higher in the back) will give you plenty of clicks to use in most scopes.

Darryl Cassel
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  #12  
Old 06-20-2002, 10:04 PM
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Re: Shimming rear base

where would a guy get one of these one piece tapered bases?
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  #13  
Old 06-20-2002, 11:24 PM
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Re: Shimming rear base

Check with Hart and Son in Nescopeck, PA
Some posters on this forum may be able to help..
Try Bernie Klocko, he's a very good gunsmith.

Later
DC
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  #14  
Old 06-20-2002, 11:38 PM
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Re: Shimming rear base



[ 06-21-2002: Message edited by: Ian M ]
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