Scopes just wear out?

williaada

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Apr 17, 2020
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340
Went to help my uncle double check his rifle. The 4round group were in a 2” area and about 6” low. I adjusted the scope to raise it 6.5” and then put a three round group and another 4 round group and the bullets were all hitting the same spot. The scope is an old Nikon at the time one of the better scopes on the market. Does it sound like the scope lost its zero?
 
Scopes have limited adjustment range, both windage and elevation. That amount varies but it's around 60 MOA top to bottom or right to left. Could be you're at the end of the adjustment. You didn't mention how many yards but I assume 100. What kind of rings and bases? Which Nikon scope? Nikon made some excellent scopes and some el cheapo ones too.
 
Addressing the post above, which mentioned adjustment range, if you had to dial a lot of windage to zero initially, then your available vertical adjustment will be less than the advertised adjustment because your erector tube will hit your scope tube after less vertical adjustment than if it was centered horizontally. If you’re not following. Draw some big circles, then draw a small circle horizontally centered in one big circle, and draw a small circle to the right of center in another big circle. Now look how high you can move the small circles before the touch the big circle. Now that you see what I’m trying to say, if you’ve adjust a long way from center horizontally to get horizontally zeroed, you have lost possible vertical adjustment range. When dialing down, your adjustment screw will bottom out early, and dialing further will require a lot of force and potentially bend the erector tube. When dialing up however, the erector tube will hit the scope tube and stop moving, but the adjustment screw will continue moving upward. This leads you to believe that you’re moved up, but you actually have not moved the image at all. THIS IS ONE POSSIBLE EXPLANATION.

Greases can degrade with age, heat, and oxidation. I would think your scope has an oxygen free atmosphere, but who really knows. If your grease has become stickier or hardened, it can make moving the erector tube require more force than originally. When dialing up or right, the adjustment screw moves AWAY from the erector tube. In order for the erector tube to move, a spring must push it against the adjustment screw. If the grease is hardened, this movement may not occur right away. When it does occur it could be sudden, and it could be incomplete. This makes for some wild differences in impacts. Don’t worry yet! First, dial your scope DOWN, and dial it WELL BEYOND its original point. The erector tube has to move down or left until it impacts the scope tube any time you dial down or left because the adjustment screw applies direct pressure, rather than moving away and relying on a spring to keep them in contact. Doing this will usually loosen up the grease.

So really, my recommendation would be to dial the scope all the way down, and all the way left, then all the way up, and all the way right. Then I would repeat the process. DO NOT APPLY INCREASED PRESSURE WHEN YOU REACH THE END OF THE ADJUSTMENT RANGES! After moving the scope all the way around a few times, things will potentially be limbered up. Bore sight at 25yds. Shoot. Get zeroed. Now move to 100yds. Zero again. Check a few times over a period of days. If the scope performs well, call it a wonderful scope. If it gives you problems, YES INTERNALS BREAK OR COME LOOSE SOMETIMES.

Usually when I want to dial up 1-2 clicks, I’ll dial down 2, up 6, and down 4 to get 2 clicks up. Dialing down loosens things up(because the tube has to move since the screw is applying direct pressure). Dialing up farther than I want to gets me good odds that the erector tube moved up at least as far as I wanted it to(a spring pushes it up), and dialing back down to the desired position gives it no choice but to be where I dialed.(because dialing down requires direct pressure from the adjustment screw). Actually I do this anytime I dial a small amount in any direction.
 
Last edited:
Addressing the post above, which mentioned adjustment range, if you had to dial a lot of windage to zero initially, then your available vertical adjustment will be less than the advertised adjustment because your erector tube will hit your scope tube after less vertical adjustment than if it was centered horizontally. If you’re not following. Draw some big circles, then draw a small circle horizontally centered in one big circle, and draw a small circle to the right of center in another big circle. Now look how high you can move the small circles before the touch the big circle. Now that you see what I’m trying to say, if you’ve adjust a long way from center horizontally to get horizontally zeroed, you have lost possible vertical adjustment range. When dialing down, your adjustment screw will bottom out early, and dialing further will require a lot of force and potentially bend the erector tube. When dialing up however, the erector tube will hit the scope tube and stop moving, but the adjustment screw will continue moving upward. This leads you to believe that you’re moved up, but you actually have not moved the image at all. THIS IS ONE POSSIBLE EXPLANATION.

Greases can degrade with age, heat, and oxidation. I would think your scope has an oxygen free atmosphere, but who really knows. If your grease has become stickier or hardened, it can make moving the erector tube require more force than originally. When dialing up or right, the adjustment screw moves AWAY from the erector tube. In order for the erector tube to move, a spring must push it against the adjustment screw. If the grease is hardened, this movement may not occur right away. When it does occur it could be sudden, and it could be incomplete. This makes for some wild differences in impacts. Don’t worry yet! First, dial your scope DOWN, and dial it WELL BEYOND its original point. The erector tube has to move down or left until it impacts the scope tube any time you dial down or left because the adjustment screw applies direct pressure, rather than moving away and relying on a spring to keep them in contact. Doing this will usually loosen up the grease.

So really, my recommendation would be to dial the scope all the way down, and all the way left, then all the way up, and all the way right. Then I would repeat the process. DO NOT APPLY INCREASED PRESSURE WHEN YOU REACH THE END OF THE ADJUSTMENT RANGES! After moving the scope all the way around a few times, things will potentially be limbered up. Bore sight at 25yds. Shoot. Get zeroed. Now move to 100yds. Zero again. Check a few times over a period of days. If the scope performs well, call it a wonderful scope. If it gives you problems, YES INTERNALS BREAK OR COME LOOSE SOMETIMES.

Usually when I want to dial up 1-2 clicks, I’ll dial down 2, up 6, and down 4 to get 2 clicks up. Dialing down loosens things up(because the tube has to move since the screw is applying direct pressure). Dialing up farther than I want to gets me good odds that the erector tube moved up at least as far as I wanted it to(a spring pushes it up), and dialing back down to the desired position gives it no choice but to be where I dialed.(because dialing down requires direct pressure from the adjustment screw). Actually I do this anytime I dial a small amount in any direction.
Thank you
 

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