Scope mounting questions

gelatine

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Hi, Folks:

I got a BIG tech question that has bother me for a long time. Really hope you can help me about it.

Assume we have a scope "A" and a rig "B".

Here's some spec of scope and rig:
Scope: Max Elevation Adjustment 65 MOA
Rifle: 20 MOA rail.
Condition:
Assume the scope is perfectly mounted on the rifle, therefore, we shall have the scope center line apart from
rifle center line of 52.5 MOA (65/2 + 20).
In this case, the space between rifle line and scope line is 52.5MOA, and space ABOVE scope line has only 32.5MOA.

However, IDEALLY, ISN'T it supposed to have more space above scope line for the adjustment, so we have more room for adjustment of bullet drop?
In this case, the ideal mounting procedure should be
1. 65 MOA (Scope elevation) + 20 MOA (Rail height) / 2 = 42.5
2. 42.5 - 20 = 22.5 MOA
3. 65 / 2 - 22.5 = 10 MOA
4. Turn the scope elevation DOWN 10 MOA from real scope centre.
5. Mount to the rifle.

What am I thinking is to subtract the rail height and leave more room for elevation.
Am I on the right way? Any ideas and comments?

Thanks for your time and help.
 
I would just bore sight it, raise your croshairs untill your satisfied. Give it a shot at 50yds. Adjust, 100 yds adjust. Then line it up for the distance you prefer.
 
I don't think you're looking at this correctly.

A 20 moa rail would angle your scope down 1/3rd of a degree giving you approximately 20 extra inches of positive (up) elevation at 100 yards with a scope at mechanical center. It's not a unit of measurement that translates to the way you're doing your math. It isn't a unit of distance between the bore and the scope center.

Changing the elevation adjustment before mounting won't change anything. You'll just end up turning it the other way when you zero your rifle. If your scope has 65 moa of adjustment and you have a 20 moa rail it will mean that to zero your rifle you will likely end up reducing the elevation adjustment to bring your reticle to the point of impact. Zeroing your rifle at a lower elevation, giving your scope more up elevation adjustment ability.

Properly mount your scope and then worry about adjustment when you zero.
 
Last edited:
I don't think you're looking at this................

Hi, Jona710:
Thanks for your reply. Really glad someone can understand what am I talking due to my poor language skill.
Yes, I understand "It's not a unit of measurement" but I just can't find better way to describe it.
And yes, I made a backward mistake.

What I'm thinking is: I know it is neither practical, nor even doable, but would this method
1. "Logically correct"?
2. Give more capabiility for adjustment?
3. When considered about LONG Range, am I sacrificing short range but giving more capability for LR?

Cheers.
 
9x19p:

Thank you very much!! I can't make myself more clear than you are.

Yes, That's what I'm thinking about. Through this method, I'm utilize my LR ability but losing
short range. I know it is not practical, but is it logically correct?

As its not possible to "tilt" the scope mount, I know the angle of scope tube is limited to a certain
angle, which is usually the "average" angle. That also leave a bit play for short range usage.

What I'm thinking is to have a piece of thicker foam pad placed underneath the scope tube at rear
mount, and of course a thinner foam pad for front scope mount.

This shall raised a bit angle of the scope and give much more play for long range. Any ideas?

Cheers
 
As is:

Scope Elevation Max up adjustment = 20 +(65/2) = 52.5 MOA
Scope Elevation Max down adjustment = 20 - (65/2) = - 12.5 MOA
Scope Elevation, center adjustment = 20 MOA

The actual performance of the rifle will be affected by the barrel, etc. However, you have enough range to get zero on paper @ 100 y. I wouldn't bother trying to shim, your scope will work fine. If you insist on shimming, you don't shim between the scope tube and the ring, you shim under the base using brass shim stock, or something similar.
 
Cosmic:

Thanks for the repy.
Yes, shim is a bit problem. To optimized the result, it is better to have shimming between scope mount and rifle
with sturdy, hard material (Thinner shim for the front, thicker for the rear).

I then realized by this way it may bends scope tube and causes some damage. The other method I have thought
is to machine off the inside of the sope ring, which is way to complicate to determine the right angle.

Anyway, still working on it to see if I can get my point proved true. Thanks again to all the opinions.
 
Damn..... Someone has invented it already...

Chargerguy:
Thanks for your comments.
Yes, it's the idea I'm looking for. Too bad it's not something new.
Indeed, Burris has done the job better than I can think of.
 
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