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Need help with Burris Posi-Align inserts |
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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Posted: February/06/2016 at 11:36 |
I'm trying to understand how to calculate the +/- .005" - +/- .020" inserts . The Burris site doesn't explain this very well, but Midway USA does. I read this to say that putting a set of the +/- .005" inserts in the front only would change the poi about 5" at 100 yards. I've read that if you orient them correctly in both the front and rear, that you could use two sets to double that poi.< ="text/" ="safari-extension://com.ebay.safari.myebaymanager-QYHMMGCMJR/54adfb7//helpers/preHelper.js">
For example. if you set +/- .010" in the front and rear rings correctly, you would change the poi 20" at 100 yards. But wouldn't that depend on the spacing of the rings on the scope tube? If the rings are set closer together, wouldn't the poi should be greater than if they were spaced as far apart as possible. Or is this just a ballpark and not an exact science? Thanks.
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Maverick2
Optics Apprentice Joined: December/30/2013 Location: N. Idaho Status: Offline Points: 176 |
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Yes, ring spacing plays a big part. Between selection of inserts and playing around with spacing between font and rear rings, you can get about any kind of ramp angle you want. I put these on a scope with limited elevation adjustment on a 6.5 Creedmoor and used these to maximize my available adjustment. I'll look for my notes relationship between spacing and ramp angle.
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Maverick2
Optics Apprentice Joined: December/30/2013 Location: N. Idaho Status: Offline Points: 176 |
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Hmmm -- here's what I sent to a friend to help him set up a scope with these rings. This may help. "... The +/- 10 inserts in back only will give you a 10/1000 inch offset, and the +/- 10 inserts in front AND back will give you a 20/1000 inch offset. If you mount the rings about 3.5" apart, the amount of total offset you have should be pretty close to the gain in MOA (ie., a 10/1000 inch total offset should be about a 10 MOA gain, and a 20/1000 inch offset should be about a 20 MOA gain...) If you spread the rings further apart, you'll get less MOA gain per amount of total offset, and if you mount the rings closer, you'll get more MOA gain. I like these rings. I prefer to space my ring mounts as wide as I can on the scope, and playing around with +/- 10 inserts in front and back, was able to gain 15 MOA which was perfect to maximize available elevation adjustment for my scope..." |
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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Thanks Maverick - so would your 3.5" ring spacing be measured from the center of the ring's width to the center of the next ring's width? < ="text/" ="safari-extension://com.ebay.safari.myebaymanager-QYHMMGCMJR/54adfb7//helpers/preHelper.js">
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Gerry Atric
Optics Journeyman Joined: April/21/2011 Location: Sweden Status: Offline Points: 340 |
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In my book (learned on this forum) ring spacing should be measured from outside - outside of the rings. Gerry Atric
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Maverick2
Optics Apprentice Joined: December/30/2013 Location: N. Idaho Status: Offline Points: 176 |
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Yes, I believe that's how I measured/calculated it when figuring it out. |
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Stevey Ducks
Optics Apprentice Joined: December/03/2011 Status: Offline Points: 266 |
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Burris Posi-Align ring inserts are wonderful and make for terrific results. Edited by Stevey Ducks - February/08/2016 at 00:20 |
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Maverick2
Optics Apprentice Joined: December/30/2013 Location: N. Idaho Status: Offline Points: 176 |
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For these rings and what the OP is wanting to do, I believe he needs to deviate from the norm and measure center of ring to center of ring if he wants the math to tell him the right relationship between insert thickness and distance between rings to get a desired ramp angle w/o a bunch of trial and error. (The way these rings and inserts are constructed, I believe the stated insert thickness is correct at the center of the ring, rather than the outside edges.) |
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Gerry Atric
Optics Journeyman Joined: April/21/2011 Location: Sweden Status: Offline Points: 340 |
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Thanks Maverick, As long as I´m learning something new this old geezer is still alive Gerry Atrick
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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That was my thinking as well Maverick, as these rings and inserts are hemispherical (I think that's the proper term) in design and would hinge in the middle of the ring - at least in my mind. < ="text/" ="safari-extension://com.ebay.safari.myebaymanager-QYHMMGCMJR/54adfb7//helpers/preHelper.js">
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