Shimming a scope

[Brazos]

I need to shim a scope but have never done it, though it seems simple enough. I have a CZ 527 with the factory rings (bases are milled into the reciever). The rifle was shooting way low at one hundred so I walked it over to the guy at the range to bore sight it. He said he ran out of elevation but got it w/i an inch at 100 yards (windage is fine). He suggested I shim it or get new rings. Since the rings are paid for I figure I might as well work with what i got before getting new ones. I used search to find different materials to use as shims. I also understand I can't shim too much w/o putting the scope in a bind. Considering the scope is out of elevation where do I need to shim? I would think I would need to shim the front bottom ring to raise the front of the scope up slightly. Let me know if I am on the right track.

Thanks,

Brazos

 

[Jim Watson]

If the rifle is shooting low, you need to raise the REAR of the scope to tilt the line of sight down to the line of fire.

If it is as far off as it sounds, you will stress the scope tube by shimming one base enough to correct. You might could shim and then ream or lap the rings into alignment, but I'd contact CZ USA first and see what they offer to do.

I am working through a similar problem on my elderly Winchester '06 that I want to set up for Long Range. The "tapered" scope bases availble for the purpose do not fit, they are two model variations out of date. So I am going to get FLG to make me a taller rear base out of blank Weaver rail and then use Burris Signature Zee rings with the spherical bushing inserts to keep the scope straight over the bases.

 

[Brazos]

Thanks

Jim,

Thanks for the advice. I did call CZ and they were nice. They said most likely the barrel was out of alignment and needed to be bent. They said try shimming if I wanted to and see if that would work for me, if not call them and arainge to send back. I think they are probably right but I am going to try to shim a little since it doesn't cost me anything but a little time. I have access to a bore sighter. He did say the same as you elevate the rear of the scope.

Brazos

 

[Jim Watson]

I have heard of bending shotgun barrels on finished guns to adjust the pattern location, but not on a rifle. No reason for it not to work, there is plenty of barrel straightening done at the factory.

Aluminum drink cans are about .004" thick and you can cut shims to shape with scissors. I had the Marbles tang sight on an old Winchester Single Shot shimmed with ginger ale can under one edge to correct windage on a sight with elevation but no windage.