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9/19/2017 7:27:10 PM
Posted: 7/8/2003 11:10:32 AM EDT
Okay, maybe the answer is simple, but...

Two rifles Browning Buckmark Carbon Fiber .22LR with Loopy Compact 3 -9 x 33.

Colt flattop with Loopy 4.5 -14 x40mm AO Tactical.

both were placed in rings and checked with level and reticle alignment bars. Appear perfectly level with horizon.


Sight - in at a certain range, windage peferct in middle of target. Move elevation adkustment turrets and then the windage changes on its own. shouldn't the windage stay the same given no atmospheric wind or changes? I'm more than confused, and upset.

At a silhouette match (.22LR) and CMP match (.223), I should be able to just use the MOA chart and adjust for POI shouldn't I? Why is windage changing?

Thanks for your help!
Link Posted: 7/8/2003 11:36:43 AM EDT
The reason the adjustment changes is simple when you look at it this way. You are working within a circle. Start in the middle of the circle, then move all the way to the left. So you are now center for elevation and on the left edge of the circle. Now, if you were to move the elevation upward or downward, your forced to move right with the curviture of the circle. This is what is happening in your scope. You are riding the inside wall of the scope. The easiest way to find the optical center in your scope is to put a mirror on the objective end of your scope. Actually place it on there... And turn the power down to about 4x, look through the scope and you will see two reticles. Turn the adjustments to where they overlap. That is your optical center. Then, shim for any elevation needed (if possible) or try swapping your rings (if they have loose tolerances). Keeping the adjustments as close to center as possible will give you the most adjustment. Hope this helps you.
Link Posted: 7/8/2003 11:41:30 AM EDT
so if i get the reticles optically centered, then when I adjust for different elevation distances the windage will remain the same?
Link Posted: 7/8/2003 1:14:37 PM EDT
If you can optically center the reticle, then you will have the full amount of travel in your scope. So, if you correct the elevation with shimming (or whatever), then you will have all of your available windage. And vice-versa...
Link Posted: 7/8/2003 1:26:46 PM EDT
[Last Edit: 7/8/2003 1:37:03 PM EDT by Boomholzer]
the vertical axis of the scope adjustment (or horizontal if you consider the elevation recticle) and the vertical plane of the "lob" of the bullet's trajectory or not inline. Another way to look at it is that your bore axis and your site axis are not in the same plane (the trajectory of the bullet and site axis is never parallel). Basically you set your rifles impact point at a set distance. In simple terms: the rifle is side-arming the bullet (relative to the vertically adjustable site plane of the scope)! Therefore when you adjust for distance or elevation, you lose your windage. Get you scope axis properly mounted to the bore axis or quit holding the rifle at a angle.
Link Posted: 7/8/2003 6:37:35 PM EDT
So, do snipers have to set the windage AND elevation for each distance? Seems like if I have the reticles level to the horizontal and the reticle centered, I should be okay? I'm getting confused. At comps and tactical sitreps, do most people adjust for both elev and wind? I do appreciate your time and help!!!
Link Posted: 7/8/2003 6:58:05 PM EDT
[Last Edit: 7/8/2003 7:04:08 PM EDT by Boomholzer]
Originally Posted By AWB317: So, do snipers have to set the windage AND elevation for each distance? Seems like if I have the reticles level to the horizontal and the reticle centered, I should be okay? I'm getting confused. At comps and tactical sitreps, do most people adjust for both elev and wind? I do appreciate your time and help!!!
View Quote
given a wind free day, at reasonable distance for the cartidge, you should only be obligated to adjust the elevation to compensate for bullet drop. You scope adjusts in only two axis, if the scope is not aliged to the bore, any adjustment of windage or elevation will give you unexpected results. For example, how do you know the verical recticle follows the same plane as the bullet to any range? (understanding that the verticle although following the varying elevation for the bullet "lob" is responsible for windage). You understand how the bullet lobs out of the barrel.........imagine a vertical sheet or plane much like the verticle recticle but with great area (a plane) down range. You have set your scope so the bullet [b]crosses[/b] this plane at you set site-in yardage. It does not follow it, therefore you see a variation in windage when you adjust for range. Either the scope rings center axis do not follow the bore (relative to the bore, not the rcvr) or the scope is incorrectly rotated in the rings. This problem is frequent with incorrectly adjusted base windage in Leupold or Redfield sold mounts with rear windage adjustment. You may need to shim your scope.
Link Posted: 7/8/2003 8:21:24 PM EDT
is there an article about how to center the scope axis with the bore axis? I use a reticle leveler. Do I run the windage and elevation screws end to end, count them, divide by two and reset to zero, then how do I know how nuch to shim? What do you shim with and how do you know what thickness? sorry to ask so many ? Just in search of perfection.
Link Posted: 7/8/2003 8:50:03 PM EDT
[Last Edit: 7/8/2003 8:51:59 PM EDT by Boomholzer]
Originally Posted By AWB317: is there an article about how to center the scope axis with the bore axis? I use a reticle leveler. Do I run the windage and elevation screws end to end, count them, divide by two and reset to zero, then how do I know how nuch to shim? What do you shim with and how do you know what thickness? sorry to ask so many ? Just in search of perfection.
View Quote
Now im come to a point where after preaching about a problem, i have no simple solution. With solid base mounts with windage I have two 1" shafts I seat in the rings to look for correct ring alignment, before i mount the scope. With a weaver type rail to the rcvr, things get complicated. Given you decription of weapons and range....you have a big problem. A bore siteing device cant help you. A full rifle rest or site-vice will. Either ignore elevation or site the rifle at 25yds using a ballistic drop table for the cartidge. For a .223 this should be around 1,5" low dependinig on the site axis height. Just ignore elevation, and proceed to 50 and 100yrds and observe windage variation in a multiple shot group. Repeat. Now the yardage is just repesentive of the cartidge. For a .22, start at 50yrds. Anyway, your seeing variance in windage and without some rig, this will show you how much. You should now have three data points on your site axis variation. Remember at one time it was zero at some yardage, you need to have that initially but ignore it. Ideally, the ctr should be the middle point with one a decent yardage before and after (50yrds). Without getting mathematical you atleast know now which way the scope needs to be shimmed or the base adjusted.
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