help with scope mounts

tylerjwitty

tylerjwitty

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i have two issues one a problem one not so much

ONE:

308 mauser with mount holes drilled off center. (not by me)
options:
redrill and tap. process how.. Weld then start over?
Mounts able to correct this?
prefer not to shim
TWO:

as of right now my 260 has the adjustments pretty much dead center 14moa up and 16moa down. i would like to make that closer to 20 moa up and 10moa down.
options:
Shim
Mounts? if so which only have a 25mm tube

thanks for your suggustions
(pls don't insult or degrade the equipment i currently have, freindly suggestions only)
 
It would depend on how your holes where off. If the holes on the front or the rear of the reciever are on a different plane than each other (i.e. the 2 holes on the reciever ring are crooked in relation to each other), you may want a good gunsmith to fill those holes and start again. If the bases end up crooked when you have them both on, you may be able to remedy this with Redfield bases (it's the style of base, not the manufacturer). These bases have screws on the rear base that allow some ammount of horizontal adjustment.
As to the diameter of your scope tube, that leaves me scratching my head. 99.999% of the scopes out in the world have 3/4", 1" and 30mm tubes. I know Redding marketed a 27mm tube for a short time before they went under, but I'm not aware of any manufacturer that made what they marketed as 25mm tubes. I've heard that the Europeans are manufacturing a different diameter now, but that was bigger than 30mm, not smaller.
1" is 2.54cm, or 25.4mm, and if you took a measurement of the tube and got 25mm than it's a 1" tube. If that's the case, then any 1" ring will work, and the world is your oyster.
Mike
 
I would suggest using a one piece base from Leupold for the M98 action. It has a shoulder on the front portion that stops forward movement on recoil. It locates the holes correctly for drilling and tapping, even if you don't end up using that base.. but it would be the easiest way to shim for height as well. You may have to have all the holes plugged and start afresh.

American scopes are mostly 1" and the larger size of 30mm, older European scopes are commonly found in 26mm.
 
For your Mauser...

I'd suggest a set of Burris Signature rings.

Go with bases that accommodate "Universal" rings, as in front dovetail and read adjustable windage. (Medium is the equivalent of low on other ring makes)

http://www.burrisoptics.com/sigrings1.html

Set rings in place.

Because of the spherical bearings, when you remove the ring caps and lay the scope in place, the bearings will automatically adjust for misalignment. Do NOT add anything to surfaces, keep all surfaces on both bearings and scope absolutely clean and dry!!!

Tighten the cap screws gingerly (meaning, without gorilla torquing), alternating side to side until reasonably snug. There should be an equal bit of gap on each side between the cap and ring base, and the cap should be square to its counterpart.

Now, when you bore sight, or start out sight in at the range...

Your first adjustment should be for windage. Loosen front ring cap screws first. Then adjust for windage at rear accordingly. Then re-snug the front ring cap screws before firing. Repeat as necessary.

Loosening the front ring cap screws allows the scope to pivot to compensate for windage adjustment at the rear. This is critical as it prevents torquing the scope tube...or, God forbid, even actually permanently bending it! (No other make of rings provide for this. It is virtually impossible to adjust rear windage in other makes without torquing the scope tube, which certainly can cause serious consequences regarding accuracy.)

Unless the drilling for bases on the rifle are wildly out of line...not likely...Burris Signature rings will automatically compensate, and do so without any need for re-drilling and/or re-machining, nor for lapping the rings...not to mention, they won't mess up your expensive scope with ghastly ring marks.

And do so without costing any more than a decent set of rings and bases.

I had an 1917 Enfield, sporterized by BSA, that caused a bent scope tube because of poor machining at the rear base surface, causing misalignment. Had Burris Signature rings been available at the time, I could easily have solved the problem in this manner, and without the services of a gunsmith.

You could also use Weaver style bases, however this would not provide the means to adjust the rear rings to help compensate for misalignment, which thus might have to be made up with internal adjustments in the scope. Depending on the severity of the misalignment, the scope conceivably could run out of adjustment before you manage to get it zeroed.

I'd certainly give this a try before spending a lot of dough on correcting the rifle itself. Almost certain this should solve the problem.

:)
 
TWO:

as of right now my 260 has the adjustments pretty much dead center 14moa up and 16moa down. i would like to make that closer to 20 moa up and 10moa down.
options:
Shim
Mounts? if so which only have a 25mm tube

Not quite sure what you are trying to do with centering the scope adjustments on your .260? You could shim the mounts, but remember that unless you are using some rings such as the Burris with the spherical centre pieces, shimming means you are jamming the scope in the rings in some way (all of the supposedly parallel surfaces are no longer parallel). Your choice, but I have never tried to centre my reticle in the way you describe, so I am not sure why you need to do that.
 
Re: Your .260...

Making a couple assumptions here, first being that you're shooting a 6.5mm because it's just about the ideal caliber for long distance targets. And second, because you're targeting out to probably 600 yds and beyond (?), you're running out of adjustment for elevation.

Burris Signature rings might give you some edge here, too.

You can buy "offset" bearing sets for the Signature rings...

http://www.burrisoptics.com/sigrings1.html (bottom of the page)

Posi-Align Offset Inserts
By utilizing Pos-Align Offset Inserts in Signature Rings, you can virtually sight-in your gun without moving the scope adjustments. By keeping the internal optics centered, you'll see through the scope all of the clarity, sharpness, and brightness that the optics designers intended for you to see. The offset inserts also correct for any misalignment caused by receiver holes drilled off center, or the bases or rings being slightly off perfect center. And for you 1000-yard shooters, the need for expensive tapered bases or shimming becomes a hassle and expense of the past.
Click to expand...

Come in .005, .010, and .020 offsets.

You can use these on the front rings to gain elevation, and if needed, in reverse on the rear rings to get even more. Instructions are provided. Also can be used for windage.

Then you can keep your scope properly zeroed as a start point. As noted in the above quote from Burris's website, the more one moves their scope off zero, the more one compromises image. The center of the glass is where the best image happens. (Parallax probably comes into play here, too...?)

25mm converts to 1"...more precisely, 25.40mm.

Standard 1" Signature rings are what you're after.
 
tylerjwitty said:
i have two issues one a problem one not so much

ONE:

308 mauser with mount holes drilled off center. (not by me)
options:
redrill and tap. process how.. Weld then start over?
Mounts able to correct this?
prefer not to shim
TWO:

as of right now my 260 has the adjustments pretty much dead center 14moa up and 16moa down. i would like to make that closer to 20 moa up and 10moa down.
options:
Shim
Mounts? if so which only have a 25mm tube

thanks for your suggustions
(pls don't insult or degrade the equipment i currently have, freindly suggestions only)
Click to expand...

With the .308 Mauser a pair of something like Millet windage adjustable rings would take care of the offset issue, provided the holes are all in the same plane (i.e. pretty darned close to a pair of parallel lines).

With the .260, although you shouldn't really need to do this in a perfect world, shimming (of one rings only I expect, with a thin piece of aluminum like a properly sized/cut soft drink can) will work here. I have at least two of my rifle's scopes shimmed in order that the centre setting on the scope adjustment (always the vertical, of course) is as close to being zeroed with minimal cross hair adjustment being required after bore sighting.

Nice equipment you have, BTW. My favourite rifle is my old PH military Mauser 98 action :)

Hope I understood your questions correctly :)

woodlotowner
 
yes thank you fellas. the mauser which i believe is a 96 will never see a gun smith again.. i got this gun pretty beat up..so think of it as my textbook on gunsmithing.

The burris mount seem like the ticket and are a good price when all is considered. "SIR SPRINGER" you are indeed correct on both assumtions.

I May just take the advice about the pop can shim. .005 is claimed to move poi 5 inches which equals roughly 5 moa which should make my scope closer to 19moa up and 11 down.

That should be shimed in the rear mount correct?
 
tylerjwitty said:
why under the scope? why not under the rear mount? or do you just mean not on top for this does nothing
Click to expand...

A personal preference thing actually. I have my old Parker Hale Mauser shimmed (one pop can thickness) under the rear Weaver base, but the other gun I have shimmed is my Ruger 10/22 and with the one piece base I have the rear scope mount shimmed in the sadle of the ring under the scope. Consider that the bearing surface area (shim/gun/ring) is best with the shim in the ring IMO, since there is a much larger contact bearing surface in a scope ring than would be available under the base on most receiver designs. The reason my PH is shimmed under the base is that the screws that came with the bases were a tad too long and were just barely touching the bolt. As it happened the gun would have needed shimming anyway with the bases/rings I had for that job so it worked out perfectly.

Yes, I mentioned 'under' the scope, but not to be a smarta$$. The tone of your posts certainly suggests you would be aware of this, but others sometimes read these posts :)

Experiment away, but always look for the simplest solution to each challenge I say, since they are often the best (and the least elaborate/expensive). Good luck.
 
Back to the original post. here is what I would do with the Mauser with drill holes off centre.
Use a small rattail file and open up the holes in the base. File just in the direction needed. Go until the holes are filed enough to enable the bases to slide, with the screws in, but loose, to where they line up. Counter sink a reccess for the screw heads, at their new location.
Clean the base(s) and the the rifle, then apply a good epoxy glue, like JB Weld.
With the screws loose and the scope mounted on the bases, bore sight it by moving the base. With it bore sighted, mark the bases, remove the scope, tighten the screws and remove excess epoxy.
An ample supply of epoxy will fill the hole in the base and when all is hardened, the base will be an integeral part of the rifle.
 
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