Yesterday's Weapons Forums

Can the gears in the scope turrets go wonky? So you can sight it in fine at 25 yards but not at 100?

I screwed up the last time I was out and didn't know where I ended up sighting in my gill gun, so today I went out intending to sight it in on the 25 yd range and then find the number of clicks needed to sight it in at 100.

At 25 yards it shot 7" high, so I must have left it set somewhere near the 100 yard setting. I clicked it down 28 clicks (in 3 or 4 steps) til it was spot on at 25 yards.

Took it to the 100 yard range without changing anything, figuring it (hopefully) would shoot about 7" low. Close. It was 8" low, just at the very bottom of the target paper. I figured I need to raise it about 28-32 clicks to raise it 7-8" (assuming 1/4" per click).

Then the fun began. Clicked it up 8 clicks figuring it SHOULD come up about 2". I could not find those holes (I may need a better spotting scope). Adjusted it another 12 clicks, hoping to hit 3" higher, for a total of 5" higher, which would still be 3" low. Again I couldn't find those holes. Did another 12 clicks for a total of 32, which should have raised it 8" and put it right on. Could not find those holes either. So I gave up in disgust and fired of my last 10 rounds. Could not find them either.

But when I went up to retrieve my target I did find 3 holes close to the bulls-eye (so yes I do need a better spotting scope ) ... and 6 holes in the backing paper just about 8" high. But also NO holes around the 6" and 3" low spots.

Could some of the gear teeth have been stripped so when I thought I was raising it 8 clicks/2" it just "wandered off the paper", and didn't come back until I got the full 32 clicks in (that would be one complete turn and almost 1/2 of a second turn)?

Is there something inside the scope that could come loose, and then correct itself at a different setting? I did check that the scope and mount were secure on the gun and the barrel was snug to the stock.

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You did not say what kind of scope you have. Is it a variable power scope?

It is better to shoot it in at 100 yards first.
I don't think they have gears, but a three point positioning system with one point a spring loaded stationary point. The other two points are 90 degrees of each other. The cross hair erector/tube will sometimes stick and not move smoothly depending on how well it was finished and might need a little tap to make it respond to the change in the xy coordinates. Some systems might have two springs loaded points or perhaps a curved flat spring to keep the tube pressed against the adjustment screws. Also if the adjustment screw threads are not machined to close enough tolerances there is room for wobble.

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Them that know, know that they know. Them that don't know don't know they don't know.

Kimfella,

That is why I said sight it in at 100 yards. Most scopes change point of impact 1/4 MOA per click at 100 yards or also stated 1/4" at 100 yards. Target scopes are often 1/8 moa at 100 yards.

The reason for a finer division on a target scope is when you start going 400 yards 1/4 click on a less expensive scope is one inch. It is only 1/2 inch at 400 yards with a 1/8 moa per click.

I am happy you considered bullet drop compensation as I normally do sight in at one hundred yards and then start calculating bullet drop at 200-400 yards using a ballistic calculator vs ballistic coefficient starting with a horizontal shot. Of course a 22 rim fire is a different matter since you normally don't shoot much beyond 100 yards.

So you reasoned it out yourself. Great.