Scope mount Help

[Klippie]

Morning All

I've had some issues with my 7mm Rem Mag For some time.
Every time I het fed up after the range, testing rounds.
So This time I started from scratch and Discovered that the front mount is not level with the Barrel or the Back mount.
The holes are not right on top of the Action.
Now this is not a competition rifle just hunting up to 300m
These are Leupold mounts and I do have Windage adjustments on the back Sights.
What are your opinions on this, How would this affect my accuracy and What are my Options here?




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[Armed Preacher]

Take it to a decent gunsmurf and have the rings lapped, the misalignment may be within the tolerances that lapping could solve.

[shooty]

If its not level with the back mount. A good Gunsmith will need to look at it

Im not sure if this will help before guys jump on this suggestion.
But I like to problem solve things.

At most engineering or hardware stores. You get Brass Shim sheets.
Various thicknesses. If you get a very thin one.
Stick a piece under the side lower as per your photo left side only.
Then tighten. When you tighten the shim will lift that part a little.

See if its then level as per rear mount.

Once you get correct height/thickness.
Color it black reinsert. Tighten and you wont see the yellow brass.

To test it in advance. i would even use a little electrical tape. Just to see.
The tape will also push flat under tightening.

But with shim in and tighten. It wont move.

This will be the cheaper quicker option.

Ive on occasion inserted shims inside rings to lower or lift a scope.
With success.

But try this maybe.

[Klippie]

If its not level with the back mount. A good Gunsmith will need to look at it

Im not sure if this will help before guys jump on this suggestion.
But I like to problem solve things.

At most engineering or hardware stores. You get Brass Shim sheets.
Various thicknesses. If you get a very thin one.
Stick a piece under the side lower as per your photo left side only.
Then tighten. When you tighten the shim will lift that part a little.

See if its then level as per rear mount.

Once you get correct height/thickness.
Color it black reinsert. Tighten and you wont see the yellow brass.

To test it in advance. i would even use a little electrical tape. Just to see.
The tape will also push flat under tightening.

But with shim in and tighten. It wont move.

This will be the cheaper quicker option.

Ive on occasion inserted shims inside rings to lower or lift a scope.
With success.

But try this maybe.

Thank You Shooty
I have some of those sheets, But this rifle has Given me Years of Trouble and Now I need a Proper Long Term solution
I've taken it to a Gunsmith
I've Got to say Every time or Let's say Most of the time when I walk into a Gunsmith or Gunshop for that matter I always want to open my own store because of bad Attitudes And Services


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[Andrew Leigh]

OK.

The front and rear mounts, are they in the same plane? i.e. do they both list at the same angle?

The front and rear mounts, are they at the same height above the receiver? i.e. if you held a straight edge on the one would it line up perfectly with the other.

If both the above are true then you are applying unnatural torque to the scope thereby affecting the performance.

If the front a rear mounts are on the same plane, and at the same height then you would have less of a problem that you may well be able to lap out.

To test the effect of the alignment do a simple check. Using thin brass shim stock, bring the scope bases into alignment. Firstly shim to ensure that both mounts are at the same height then shim on the sides to correct for "level". When you return you scope to the mounts and go shooting you should see a significant improvement with the scope no longer "torqued". If this is the case you now know what you need to do. Refit the mounts correctly.

[Dick]

I saw a lot of problems of this sort. It needs a logical structured diagnosis. A spirit level reading on the barrel rib doesn't prove anything because there's no guarantee that the rib is level. You need to compare both bases in two ways :

(1) check them longitudinally with a straight edge (cheap steel ruler will do). Any significant difference of height will be apparent. If it doesn't show any observable difference it doesn't mean there isn't any but they will be close enough for lapping to take care of. If there is an observable difference in height, it means that the bases are mismatched. That's more common than you might think. The only remedy is a new matched pair. Forget about shims - they are OK for testing but I don't favour them as a permanent fix.

(2) check them crosswise with a spirit level. It seems that you have done that but it wasn't clear what it showed. If, for example, the front base is tilting leftward (seen from rear) compared with the back base, the scope will point visibly left of the barrel. If it is bad enough it will not be possible to bring the scope to point of impact, and I have corrected several like that. The second effect, of course, will be that the misalignment will be too much to correct by lapping. The third will be that the rings will grip the scope by their edges, ie no grip at all, in fact tightening the rings may dent the scope tube.

There are two more checks that can be done with a steel ruler :


(1) If the ruler is laid flat on the bases it will show if they are not level with each other


(2) If it is laid flat on the bases with its edge carefully bisecting the screw holes, a squint along that edge from behind the rifle will show if the holes are parallel with the bore. It may need a second person to hold the ruler while you do the squinting. The same thing can be done with a length of cotton pulled taught. This test is best done both with the bases on and off the rifle because that will show whether the fault (if any) is with the bases or the tapped holes.

I must say, though, that a significant fault of that sort should have shown up in visible skewness of the scope. My book includes two actual examples of exactly such a condition.

If the bases are faulty replace them. If the tapped holes in the receiver are skew to the bore, the only solution is to purchase a pair of bases, one of which has no holes, so that the holes can be drilled off centre by the required amount which can be calculated. Or get the base manufacturer to drill them. That will be much easier with SA made Thor mounts than imported mounts. Although, if memory serves, some US manufacturers will supply blank bases.

Finally, corrections of the sort I have described usually leave the rings misaligned slightly more than normal, but within lapping limits, just needs a bit more lapping. Rings should always be lapped anyway.

I don't think your problem is insurmountable - just needs accurate diagnosis and careful work. I loved those challenges.