This maybe should go in Gunsmithing--but:

I changed scopes on My M-70 416 B&M- I am using it for most of my hunting now--so I wanted something with a bit more Magification so i went with a Trijicon 3x9 to replace the 1x4 that was on it. the problem i am having is to get it sighted in 2 in high at 100 yds I have used up all of the elevation available in the scope adjustments.

- leopold QRW mounts

So:

1: Will this damage the scope?
2: Is it possible/advisable to shim the rear mount to level the scope a bit more?

Thanks

SSR

If your rifle shoots to the bore or near enough to it then centre your scope adjustments and then shim one of the rings on its base left, right, up or down to get the cross hair centred on target when the rifle is bore sighted.
Results will be poor when adjustment is almost out to the limit vertically or horizontally.

quote:

Originally posted by Sean Russell:
This maybe should go in Gunsmithing--but:

I changed scopes on My M-70 416 B&M- I am using it for most of my hunting now--so I wanted something with a bit more Magification so i went with a Trijicon 3x9 to replace the 1x4 that was on it. the problem i am having is to get it sighted in 2 in high at 100 yds I have used up all of the elevation available in the scope adjustments.

- leopold QRW mounts

So:

1: Will this damage the scope?
2: Is it possible/advisable to shim the rear mount to level the scope a bit more?

Thanks

SSR

First off make sure you are moving the adjustment in the correct direction; it is not the first time that has happened.

If you have to shim, lap the scope rings after to ensure the alignment won't put any stress on the scope. You can take it one step further by bedding the scope to the rings with ample release agent of course.

Jim

Thanks-- yes worked it in from 25 yds to 2 in high @100. it really did take up all the adjustment-- I love the scope or I would send it back to factory--truthfully, Trijicon has good products but I have not been happy with their customer service-

will look into lapping rings--was hoping that with a thin shim i could back off full elevation, but as always there is no such thing as a free lunch.

Thanks again

SSR

Probably should approach this logically. It is either a function of the scope, the bases, or the receiver. If it's the scope... do other scope (s) require a similar large amount of elevation or is this the only one? If this scope is the only one, then it's likely it is the scope. Might be a manufacturing defect, or maybe it was dropped or jarred to the extent that it knocked something out of whack or bent the eyepiece threads.

As to whether it's the bases or the receiver.... install the bases, then lay a good accurate straightedge over them. See if one appears higher than the other. Then install a different set, check the same thing. If both show the rear base consistently lower than the front for example, then it's probably the receiver that is off. If one shows even and level and one set is off, then it's most likely a difference in the bases.

As an example, in a new FN Model 70, I could not get a Leupold 70A 1 piece base to install level. I tried 2 different ones and when the front screws were tightened, the rear of the base,would lift 20 t 30 thousandths off the rear bridge. In this case I felt that it was the base since I noted a small amount of curvature in each (warped in machining?) so i altered the front section to allow full front and rear contact . It bore sighted and zeroed fine after this. From time to time I have noticed 2 piece bases that,don't appear to height match using the ruler test, and will substitute
different ones or alter or shim the ones I have. After all, you can't do much if the receiver is out except to fit bases to it .

Base manufacturers have to keep up with minor dimensional changes that may have occurred over the years with rifle receivers, or perhaps not, and I would imagine that the various iterations of the Model 70 would have presented minor differences over the years. So I'd think it quite possible to encounter a height mismatch with bases somewhere along the line.... but it's all worth checking out.

Are you using the same rings and bases you used with your 1-4? If so, I doubt that it's the rings or the bases. If not, try another scope in the same rings and see if you get similar results (your 1-4 for example).

There are bases available with up to 20 minutes of elevation built in, for use with long range rifles, to keep the reticles from being adjusted close to the limit. Both Leupold and Warne have versions of this base. That might be a solution to your problem.

You will be surprised just how thin a shim is usually needed to to get a scope back on to alignment with the bore. I have had to shim quite a few over the years particularly when working with the older reticule moving scopes (Kahles etc.) where you try to get the reticule centred in the sight picture when the rifle is shot in. And I have had to do this on factory drilled rifles, some expensive ones at that.

The very small amount of shim thickness involved in moving one ring on a base is not going to damage the scope and I have never ever lapped rings - no need to complicate a simple process.

Currently I have had to shim one of the quality steel rings on a Brno ZKK rifle which has built in bases for scopes. The spare scope I was trying on this rifle ran out of horizontal adjustment so I used a small piece of brass shim cut to fit on one side of the front dovetail. By boring a 6mm hole through a piece of broom stick and clamping this in the rings I could see how far off the bore the scope would be and could then see how the shim I chose bought the scope back into alignment with the adjustments set midway in their travel.

Just glued the shim to the ring so if the scope is removed the shim is not lost.

Do the straight edge test. My last M70 Express got fitted up with Weaver bases and the rear wasn't even close to high enough to line up. A few trips to different stores produced another base with the same number stamped on it that was completely different in height. An ient dusty bag. I'll bet on a base mismatch due to variations on the receivers. Another action that's famous for the same thing is the Vanguard. I've done a lot of fit and try on that one to avoid shims.

Just a thought. You might look into the Burris Mounts with the poly inserts. You can make some pretty serious adjustments with the inserts.

Sean,
That's the gun you use a lot and may in fact save your life some day when some old cow elephant wants to two step on your body...

I would have the rifle action surface ground and hand fitted Talley bases with the scope adjustments set in the middle of the focal plane of your scope, so you have full adjustment in windage and elevation.

I had Jack Belk do this to one of my rifles and its absolutly awesome..I sent you email photos of my G33-40 Mauser he did for me and it appears to be a double square bridge but its not, they are drilled and tapped. Add to this I can detach the scope and it will return to "exact" zero every time..most QDs will just return within 2 or 3 inches. A scope that's zeroed at the edge of its focal plane or adjustments is a scope looking for trouble..

I believe this to be so much better than shims, shims IMO are a patch job.

Ray

i certainly agree about the importance of getting done right.

I don't like talley bases or rings, we can get leopold QRWs to work with a good gunsmith.