Help with angled bases

damadama

damadama

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The rifle is a Sako TRG-S in 338 Lapua. The bases and rings are Optilok and the Scope is a Bushnell 6500 2.5-16x42. As the Optilok rings have an insert similar to the Burris to compensate for slight mis-alignments, I plan to raise the rear ring by placing a shim between it and the base to get a sloping base. Can anyone tell me how thick the shim needs to be to give me 20 moa?
 
RingMath.jpg


And the engineer in me comes out.

Be advised I've had more than a few beers tonight so if my math is RTFO someone let me know.

That being said you should be able to calculate the shim thickness based on the diagram above.

For example: if your rings are 25cm apart (ensuring you measure from the same point on each ring) the calc is as follows:

Shim thickness = .005818(Ring Spacing)

Shim Thickness = .005818 (25cm)

Shim Thickness = 0.145445cm

Convert units and calculate to additional significant digits as required.
 
damadama said:
The rifle is a Sako TRG-S in 338 Lapua. The bases and rings are Optilok and the Scope is a Bushnell 6500 2.5-16x42. As the Optilok rings have an insert similar to the Burris to compensate for slight mis-alignments, I plan to raise the rear ring by placing a shim between it and the base to get a sloping base. Can anyone tell me how thick the shim needs to be to give me 20 moa?
Click to expand...

This is crude but very effective from experience.
A 5/16s flat washer placed beteeen the base and the ring will give you about 25 moa.
I have used a washer on my go to Sako AV hunting rifle for about 20 years now. I did have to make said washer D shaped so that nothing protruded.
Make sure your ring screws are loose to allow the inserts to move with the scope when you lock the rings onto the dovetail, then tighten them down.
 
Rick, not trying to start a fight but you raised the rear of your base over 0.3125" or 312.5thou or 5/16"?

Where could you even find a washer that thick ????? Ah, you Alta oil guys - go big, go bigger :)

That would sure give you a nice long range zero.

Also, what did you do with the other three bolts?

Isn't LR fun?

Jerry
 
mysticplayer said:
Rick, not trying to start a fight but you raised the rear of your base over 0.3125" or 312.5thou or 5/16"?

Where could you even find a washer that thick ????? Ah, you Alta oil guys - go big, go bigger :)

That would sure give you a nice long range zero.

Also, what did you do with the other three bolts?

Isn't LR fun?

Jerry
Click to expand...

Jerry I think a trip to the hardware store is in order. Ask the clerk for a 5/16ths flat washer, he will give you a flat disc with a 5/16th diameter hole in the middle of it.
The hole diameter in the washer is 5/16th" NOT the thickness of the washer. The 1s I buy by the thousand from Acklands are .025" thick which comes close to 25 moa on an AV action.
Not sure where you found 3 more screws?:eek:
 
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