starting adjustments for a 1712

[frog5215]

I've been fooling around with Burris rings with eccentric inserts.
A +.005" or .010" in back (or the minus in front) will help.
Prevents any need for ring lapping.
An Anschutz 2001 air rifle has , must be, .080" height difference between front and rear dovetails.
With rings less than 4" apart, it's still possible to mount a scope without kinking the tube, and with no tube stress at all.
If you need much shim, it's not really very good for the tube.
Of course, with the air rifle, it wasn't possible to get a SETTING without eccentric inserts; @ 10M I was only about 4" high with the elevation screwed all the way down.
With +.020" shims on bottom in front and on top in back, the 20yd setting came about one turn up from bottom.
By all means set it up plain; if it won't zero, then start shimming.
I'm just saying that if shimming is needed, Burris Signature Zees are great.

[Evelio Mc Donald]

Innocent Mary
I don't make scope bases or rings, I leave that to the guys that have CNC machines, I only use BKL rings on all of my rimfire guns.
I sure be glad to see you in Houston in March.
Evelio.

[Innocent]

Thanks for the invite Evelio, will have to see how the old man is holding out he is back here in FL for some more tests....he thinks he'll be back in NM by Feb, I'm a little more realistic when it comes to heart work.
Mary

[blueline]

@ innocent... Can I sighn up to be one of your junior shooters???? I definitely need professional help!!! ;)

Blueline

[Innocent]

Blueline...I do not claim to be professional but you are more than welcome to jump in the mad house of juniors anytime.

Innocent

[RBriscoe]

Mary,

Dick Thomas used to say that you would not damage a scope tube if you were shimming less than 0.020" or 0.025" so, if nothing else, shimming it 0.010" or so should not harm anything. I have had to shim some scopes and several other people I have known have had to do so as well. That is not to say that all smallbore guns need to be shimmed, but it is not surprising, at least to me, when one does.

I had bad experience with the Burris rings some years ago, but several people have told me the ones of recent manufacture work well. The basic idea of the floating centers is a good one...they borrowed it from Arnold Jewell.

As to why some rifles need shimming and others do not, there are a million theories, but a lot of them have to do with hand polishing of the exterior of the action (and scope, too) which introduces unknown and unpredictable variables. Barrels are sometimes just plain screwy, even ones from the better manufacturers. The "hole in the middle" is not necessarily in the middle and does not necessarily exit the muzzle parallel to what you think is the centerline of the barrel. And some of them are just plain banana shaped. The funny thing is that some of the odder ones shoot just fine if you can get them on target. A bench acquaintance once told me that the best barrel he had ever sectioned had the centerline of bore move about 0.0015" for every inch of barrel length so things do move around.

My 1712 lines up just fine if I use the dovetail to mount the rings, but will not even cut paper at proper distances if I use the screw holes on top. (Thanks, Anschutz.) If I ever get around to rebarreling it, I am going to get the holes blanked and redrilled.

I have used a fair number of 18-40 Leupold/Premier scopes and it is not terribly surprising that they probably need shimming more than some other scopes. I have even had "The Tucker Mod" done on some of my scopes to stabilize them as you go up & down in elevation. A great many of the Leopold scopes do not actually change the position of the reticle during the last turn of elevation.

If you are happy with your scopes, don't ever look through them with a collimator while working the knobs. It can be pretty scary.

Oh, and one more thing. "New" does not necessarily mean "good". One of the worst scopes I ever had was a brand new out of the box one which had some loose lenses and such. I got fixed under warranty, but it took a trip to an indoor range to finally determine what was going on.

Aren't scopes fun?

Rick