Is This Going To Be A Problem?

Joined
Jul 31, 2020
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Pflugerville Texas
I'm swapping optics between my 308 and 6.5x06 . The 6.5 originally had a Leupold STD mount (see pic) with a dovetail in the front and flat base in the back. I couldn't find 34mm rings to match the existing STD bases so the local gunsmith swapped them for Weaver Top Mount Bases (#48227 and #48045). When I installed the bottom half of the rings on the bases , I went to level the rifle and noticed that the two bottom rings aren't level with each other. It's possible the original mount has been the this way all along, I didn't reinstall it to check but now I need to know how much this matters. I understand that the optic needs to be in line with the barrel and the reticle needs to be level and all but how much of a difference does the cant of the ring make? Thanks for your help !
 

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Bucklowery

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Jul 1, 2013
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northwest florida
I buy canted bases for most of mine on purpose but they are all one piece. It helps with having more adjustments for dialing dopes.

Thanks

Buck
 

ShtrRdy

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Jan 14, 2012
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High Plains
I think you would have to figure out if the surface of those two rings are in the same plane so that the scope wouldn't get damaged. Try carefully setting the scope into the rings and then look at the ring to scope interfaces to see if there are any gaps.
 

rlspahn

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Mar 24, 2008
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102
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Texas
It looks to me that you're describing a rotation of the rings around the centerline of the axis of the scope, rather than the front-to-rear alignment of the rings to each other (scope cant). With a 2-piece scope base, it's possible for the front and rear bases to be rotated out of alignment with each other. Remove the rings and check the level of the bases in the same manner that you checked the level of the rings in the photo.

If the bases are not level with each other, then you will have a problem moving the scope between rifles. The rings will try to twist the scope as they are tightened to the bases of the other rifle. A single-piece picatinny base can help, but it can also be twisted when it is tightened to the receiver. You would need to bed the scope base to the rifles to eliminate this twist.

I hope I've explained this clearly.
 
Joined
Jul 31, 2020
Messages
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Pflugerville Texas
So, to update this post. Turns out that the holes that were drilled in this Mauser action for the original one-piece Leupold STD ring base do not line up perfectly with each other when replaced with a two-piece base set. We'll just have to see if this has any discernible effect on accuracy. It's been tack driver over the past 50 years with two different optics so hopefully that will continue with the new one. Thanks for all the feedback.
 

LDHunter

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Jun 21, 2001
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805
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NW Florida Piney Woods
So, to update this post. Turns out that the holes that were drilled in this Mauser action for the original one-piece Leupold STD ring base do not line up perfectly with each other when replaced with a two-piece base set. We'll just have to see if this has any discernible effect on accuracy. It's been tack driver over the past 50 years with two different optics so hopefully that will continue with the new one. Thanks for all the feedback.
You may have more than one issue here. You might not only have rings that aren't aligned with each other which will mean that they will immediately put torque on the scope barrel and probably dent the tube voiding the scope warranty but you will likely have the scope pointing no where near the POI of the barrel which will mean you'll have to use a LOT of adjustment to get on target and your scope will not be operating anywhere near the center of the mechanical adjustment range which can cause a lot of issues each time you try to adjust your crosshairs and the scope might not hold zero even if/when you finally do get it adjusted.

IMO you might need (if possible) to start all over and drill new holes for a picatinny rail forward or back of the old ones that are aligned properly with the bore and THEN mount a picatinny rail. This will require a gunsmith with extensive experience with Mauser actions.
 

jrock

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Mar 12, 2014
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1,242
Location
Idaho
+1 At the least, you can buy some shim stock and shim up a side of the base and then bed the base. I've had to do this to a number of old guns that either don't fit modern base options or the screws are out of alignment. The Wheeler scope lapping kit has alignment rods that will identify issues. Also as others mentioned, try swapping ring positions and turn them around. You might get lucky with an alignment configuration.
 

Mike Matteson

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Jun 26, 2017
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1,058
and get decent levels....
You can stack the levels on top of each other to see it they read the same. The main thing is are they reading the same to start with. That will get one problem out of the way. If there a difference note it and remember what it was and move on to checking you bases.
 

ntsqd

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Nov 16, 2015
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1,044
Location
Upper SoKA
What I'm seeing is that the rear ring is rotated left high. It looks like the problem could be at the ring to base interface as I think that I see a small gap on the LH side and not on the right.
Don't bother with "alignment bars" as they are misleading and inconclusive, go straight to a lapping bar and see how it fits in the rings. If necessary lightly lap the rings bottoms and look at where it bright-spots vs. where it does not. The amount of misalignment that I'm seeing shouldn't be corrected with lapping, need to get them much closer than that.
 
Joined
Jul 31, 2020
Messages
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Location
Pflugerville Texas
This situation makes a little more sense when you consider the original type of ring base this rifle had. With what I'm calling a '1-piece STD mount' (which may not be the correct term), the front ring fits into a dovetail but the rear scope ring sits flat on top of the base and is held in place by windage screws on either side. With this type of mount, the slight cant of the base was likely corrected through the windage screws. I think in light of what I'm seeing with the 2-piece ring base, I'm just going to re-install my 3-18x with the 30mm tube so I can keep the original base. Besides, I'm interested in the new 375 Raptor cartridge and may just save my 4-24x optic for that new build. Thank for all the feedback !
 

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Mike Matteson

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Jun 26, 2017
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That base looks a lot like a Leupold one piece mount. If I remember correctly Redfield made about the same one piece mount too. I like them because I could adjust the rear of the scope if it wasn't completely lined up with the barrel on left to right. Burris signature rings are some of the better or what's being claim. I don't have any experience with the Burris rings presently. The locking dovetail front mount I place the hold ring in and turn it to lock it in place. I wouldn't put the ring on the scope and turn it into position. I felt that it would place undo force on the scope itself. The other is there was some claim that the one piece mount help strengthen the action some. Whether that is true or not I don't fully know.
 

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