Scope adjustment on 10-22

[gerryb158]

Need a little advice or coaching on this problem. I installed a Nikon 4-12-40 scope on a new Ruger 10-22 using a one piece mount. When sighting in, the rifle shot very low so I had to crank the elevation adjustment (what I consider to be) quite an excessive amount. Say at least fifty clicks or a bit more. I was at 50 yards. I did get into the center of the target but still curious about this much adjustment. I'm thinking about possibility of putting a shim either under the mount or in the bottom of the split ring. How to do this? In order to raise the point of impact do I want to raise the back end of the scope? Any suggestions on a good material to use for a shim? Or, just leave the caps back on the scope and forget the whole thing? (Worry-wart) Any suggestions appreciated. GB

 

[DGW1949]

First thing I do with a new to me scope is insure that the reticle is actually centered before I begin the sight-in process. Where the first bullet strikes from there tells me whether I want to shim first, or simply adjust.

Hope that helped.

DGW

 

[Chief 101]

do what DGW said, center the reticle first...that tells you where everything is. If it was centered you need to shim the mount or make sure the rings are secured properly.

 

[JFB]

I agree with what DWG state, but I have some illustrations

with the scope centered in its adjustment, the point of aim (POA) will be parralel with the scope tube. most "standard" bases and rings will have the scope tube parralel to the barrel IF mounted proper AND the barrel is mounted in the reciever proper.

If every thing is correct, your point of impact (POI) will be low to your POA by the elevation the center of your scope tube is above the center of the rifle bore plus the bullet drop for that range. for example if the scope is 1 1/2" above the bore, and you are shooting at 50 yards with a HV ammo that has a drop of ~3", thus POI about 4 1/2" low

If you are less than 4 1/2" that is a good thing. if more, that might become a problem. there are non standard rings and bases that angle the scope tube (front down) so that you don't have to use as much adjustment to zero. you might have seen bases advertised as 10MOA or 20MOA which refers to the angle down they have machined. besides bases, the Burris Zee rings have a plasitc insert that goes around the tube that is thiner on one side and thicker on the other to put the scope in the rings at an angle.

once you know how much your scope actually needs to be adjusted from its center setting, you can compare the scopes specs to see if zeroing is possible with out making changes to the rings and base. for the 4 1/2" off at 50 yards you will need to adjust about 9MOA. If the clicks are 1/4" at 100yards that will mean about 36 clicks.

PS as for the barrel not being mounted parrelal to the reciever, here is a recent discussion that implies there is a significant error that effects windage
http://www.rimfirecentral.com/forums/showthread.php?t=579850

 

[rugerjunkie]

A mount allowing you to use burris signature rings would help a lot in this case. The rings have inserts that allow shimming with different offsets built into the inserts.

 

[gerryb158]

It looks as if I am in the "starting over" situation. I know this is the dummer question, but how do you find the center of the adjustment range? Just crank all the way in both directions and find the middle, I assume? (don't like that word) I am using a "Weigand Integra Mount" that is made for the 10-22, the rings and base are one piece and there is no adjustment in the mount, except the possibility of shimming the front or rear. Or shimming the lower part of either the front or rear ring. I hope shims are not necessary. There is no problem at all with horizontal adjustment as this has been very very close from the beginning. I certainly don't want to replace this scope base. Thanks for all the input so far. Gerry

 

[rugerjunkie]

Ive never tried it but supposedly you can take a scope and put the end on a mirror and if it is optically centered you will only see one set of crosshairs. If you see two...adjust till there is only one. You prob need a small flashlight and 3 extra sets of hands to do it too!

But otherwise yes , just count the clicks from full left and right , divide by 2 and set it in the middle.

I use Burris Signature rings on everything I can possibly use them on. They are nice! And if shimming is needed , I think they have the best system out there with the different inserts for the rings. Another bonus with the nylon inserts is that you will never scratch a scope tube with them.

 

[JFB]

I had good luck sanding the bottom of the base to give me about 25MOA. I used a 3" PVC drain pipe to match the radius of the reciever

 

[gerryb158]

Thanks again. Good suggestions I had not thought off. Unfortunately it will be several days before I can get back to the range to see how things improve (or not) after re-zeroing the scopes vertical adjustment. If that doesn't help I will further investigate installing shim material under the mount or sanding the mount base as suggested by JFB. I'll let you know how this project turns out.. Gerry

 

[bentblade]

I'm just guessing here but your scope probably has 1/4" adjustments and that is probably at 100 yards, so at 50 yards you probably are getting an 1/8" change. So 50 clicks to move maybe 6" wouldn't be out of the norm. Doesn't mean you wouldn't have to shim the mount just a possible explanation.
Now if my thinking is off someone please correct me. The more I learn now the more I have to forget later.
My only ? is how much more adjustment do you have and will it be enough for the distances you intend to shoot. If you have enough and the reticle is still centered why worry about it.