Trail XL scope out of down adjustment

[wahoowad]

I had reason to suspect the original Centerpoint scope that came with my Trail XL so swapped it with the exact same scope that came on a friend's new Remington Summit rifle (he is putting another scope on it). I tediously cleaned all the screws with denatured alcohol then mounted the scope, tightened all the screws evenly and applied loctite to all when done. I let the loctite dry for 48 hours then tried to sight it in this afternoon.

The windage only needed a small adjustment. The elevation was 4.25" high at 10 yards so I adjusted down 30 clicks and refired. It came down about an inch so I adjusted down another 30 clicks...POI dropped 1 inch....adjusted down another 30 clicks. After 90 clicks down I was still 1.25" high so I started to apply another 30 clicks down but the turret knob started getting firm around 15 clicks so I stopped. I assume I was running out of adjustment. Now I don't know what to do. The mounts and weaver rail are not adjustable. I have no shims. Should I have more clicks to go and something is wrong with this scope?

[rocker1]

mine was like that i used some old photo film for a shim. so far everything has been good. thanks david

[gamo2hammerli]

Cut one or two pieces of plastic from a soda bottle and shim the front end of the scope.  That's a cheap fix and should give you quite abit of "Down" adjustment.

[wahoowad]

wouldn't lifting the front of the scope also lift the POI? If I shim, I was thinking I would shim the back?

Does this suggest I have a faulty scope? Maybe I shouldn't move forward with this one?

[longislandhunter]

Stanley is correct.... if you need to lower the POI then you shim the front of the scope.   If you needed to raise the POI then you would shim the rear of the scope.    I know, it sounds backwards but don't fight it, just go with it    

My favorite shimming material is 35mm film negative and usually 1 or perhaps 2 pieces will do the trick.  Just be careful when you tighten down the strap screws.... don't overtighten or you could damage the scope.  

I've had to shim 2 of my RWS rifles and it worked great.    

Jeff

[wahoowad]

OK, took awhil but I finally wrapped my head around how the front ring is what will work. I saw Charlie's recommendation in the library. I believe he said to place it between the scope rail and the bottom the scope mount. Would this work for the Trail Weaver rail and rings? I'm thinking not and that I will have to place it under the scope main tube on the bottom of the ring.

[longislandhunter]

You'll have to place the shim/s directly under the scope tube.  I like to use the 35mm film negative because it molds itself perfectly to the curve of the scope tube.  When you tighten the screws on the top straps of the scope tube you can certainly make them nice and tight, but DO NOT over tighten them  !!   Even those very thin shim cause the scope tube to lie at a less than level angle in the mount cradles and over tightening can cause damage to the scope tube.  

Jeff

[wahoowad]

Do you think it is Ok to double up the negative material? By this I mean cut two pieces and lay one on top the other. I looked at the Charlie shim guide and feel like I need more than 1.25" adjustment at 25 yards. I probably need twice that so I can get back towards the midrang of my elevation adjustment. I do not like having the internal adjusment spring compressed so much.

Alternatively I could cut up an aluminum can but my micrometer only goes to hundredths and not thousanths so I can't get a good measure of it. The film negative is supposedly 0.005 and all I can read is 0.01 on my micrometer. I would think the soda can would also be in the thousanths range.

[airiscool]

Try to use the least amount of shim that will get you close. The more shim you add to one end of a scope the more likely there will be a bending stress on the scope tube. Too much shim may get the scope in adjusting range only to cause internal scope problems. I'd say, try one layer first and see what you get.

Paul.

[rocker1]

don't forget to center the  adjustment like  i did. thanks david

[wahoowad]

rocker1 - 5/19/2010  5:24 PM  don't forget to center the  adjustment like  i did. thanks david

Are you saying to optically center it?

[rocker1]

yes, i believe you said you had it turned as high as it would go, you need to turn it back to center. its bottomed out now so back it half way should do it.

[rocker1]

sorry about that you said down but it will be the same difference, thanks david

[wahoowad]

Removed the scope, optically centered it, added one film shim under the front of the scope, reinstalled. I backed off to just under 20 yards and started sighting in. I had to apply 140 clicks down to get it vertically zeroed. This time the turret did not get firm so maybe I was in a better starting position given I had optically centered it, but that still seems like a lot of clicks. Should I go back and add another shim? Or add a different material? At this point I wish I had 3 pieces of negative film under it but that doesn't sound good either. I don't know what to do. Bashing it with a cinderblock sounds fun right now.

[Perry50]

It is always recommended to keep the scope as close to at its optical center for the best performance. I would add another layer of film to get it as close to optical center as you can without adding bending stress to the scope.