Misaligned scope bases

[NateG]

At least, I think that's the problem. With the scope mounted and ajusted to the far right, my new-to-me rifle is off by about 18" at 25 yards. What's the usual way to fix that? Shims in the rings? Windage adjustable rings? (any suggestions?) Something else?

Thanks,
Nate

 

[Jim Watson]

18" at 25 yards is gross error indicating some sort of major manufacturing failure somewhere in the outfit. What kind of rifle, mount, and scope?

Burris Signature rings, available for "standard" (Redfield type) and "Zee" (Weaver type) bases, have plastic inserts that are available in eccentric sets to make rough adjustments, but not of that degree.

 

[NateG]

It's a mauser sporter. The rings seem line up with each other, just off to the left. (It's not noticable, except when the scope's on and either shooting or boresighting)

The base is a two-piece weaver-style base with some cheapie simmons rings. The scope is a cheapie tasco that worked just fine on the rifle I took it from.

If the rings are 4 inches apart, then, by my calculations, I have to shim one ring by .08" or each by .04". ( 4" / (25yd*36in/yard) * 18") This doesn't seem like all that much. Would shiming the scope by this amount (I've got some aluminium sheet that's something on the order of .04") hurt the scope? I'd like to try that one first (it's free, the other requires money and waiting for stuff to arrive in the mail), but only if it won't bend the scope. Oh, it's 7x57, if recoil is a consideration.

Again, thanks.

 

[Jim Watson]

That is about twice the adjustment available in the Burris rings and is a huge error in a scope mount installation.

I don't know if you can get .040" per ring in there without dinging the tube. I'd give it a try, what is there to lose?

I saw one that had at least part of the misalignment in the rings and could be fixed by reversing one of the rings on the scope.

 

[ocabj]

The most likely cause of this issue is the scope mount holes aren't straight in line with the bore.

The next likely cause is that the scope base itself is not in line with the bore.

The simplest solution would be windage adjustable rings, if you can find some that exist for a weaver base.

The next solution would be to switch to standard style base and rings. This will allow you to make windage adjustments at the base.

 

[fineredmist]

Bring the gun to a smith who knows his business, weld the holes and start fresh. You can mickey mouse this and it will never work right. Bite the bullet.

 

[hoghunting]

If you are still planning on using shims, don't put them in the rings where the scope mounts. You need to put them on the side of the base inside the ring where it attaches to the base. Sounds as if someone screwed up drilling holes for the base.