Picking scope ring height

GA Firing Line

AtlMedic

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Mar 25, 2015
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i need new rings for my .308. The ones I have on it force the scope too far forward but I want to keep it as low as possible but move it back.

Is there a trick to figuring out the right height I need or is t just trial and error?
 

Laufen

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Trial and error, just make sure a business card will slide between the objective lens and the barrel.
 
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Laufen

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It's a savage axis and a bushnell scope. I can try and find the exact scope model if needed.
@SkipD
Usually a 40mm obj will require medium rings, but there are other factors to consider like barrel contour and the thickness of the scope body.
 

AtlMedic

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Usually a 40mm obj will require medium rings, but there are other factors to consider like barrel contour and the thickness of the scope body.
I think I have medium now. I'm probably just going to pull them off and take them to the store and buy some a little taller.
 
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cmshoot

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Measuring for scope rings

1. Mount your base to the rifle.

2. Stack washers (or pennies, nickels, quarters, etc) in even stacks on the mount about where your rings would go. Build the stacks up until you get the scope at the ideal height that you want.

3. Take one of the washer stacks and measure the height (preferrably with calipers). If you don't have calipers, use pennies to build your stacks. The average penny is .0593".

You will now have your ideal saddle height (top of the base to the bottom of the scope body or tube). In the accompanying photo, that is height "B".

You will want to purchase a set of rings with a "B" height as close as possible to what you measured from your stack of washers

When purchasing your rings, if they are sold using height "A" (top of base to center of ring) then you will need to:

Add .5" to your washer measurements if you have a 1" scope tube

Add .59055" to your washer measurements if you have a 30mm tube

Add .66929" to your washer measurements if you have a 34mm tube

Add .688975" to your washer measurements if you have a 35mm tube


Alternatively, you could subtract those numbers from the "A" height of the scope rings manufacturer's specs and that would give you the "B" height, it'll work either way.


IMG_4339.JPG
 
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cmshoot

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Here are the "B" heights (see pic above) of some common 30mm scope rings.

Seekins Low .229
Badger Ord Standard .232
Farrell Ind Standard .243
Leupold Mk4 Medium alum .249
Smith Ent Low .250
Seekins Medium .279
Badger Ord Medium .294
Nightforce Low .300
Seekins High .329
TPS TSR Low .334
Seekins Ultra High .379
EGW Standard .400
Nightforce Medium .400
Talley Tactical Low .409
Badger Ord MedHigh .409
Farrell Ind High .443
Leupold Mk4 High .469
TPS TSR Medium .484
Smith Ent Medium .500
Badger Ord High .534
Nightforce High .535
TPS TSR High .634
Talley Tactical Medium .684
Nightforce Ultra High .782
Badger Ord Ultra Ord .787
Leupold Mk4 .809
Talley Tactical High .834
 
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SkipD

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Unfortunately, the specs don't show the diameter of the front end of the scope.

The minimum thickness (at the center line) of appropriate bases would be 1/2 the diameter of the front end of the lens minus 1/2" plus a little clearance space. Do the calculations in decimal inches and then use a caliper to measure potential bases that you can find at a store.

For a demo, assume the front end of the lens is 1.75" in diameter. The minimum thickness of the bases should then be (((1.75/2) - .5)+.15) or 0=.525" assuming you wanted 0.15" clearance between the barrel (actually the surface the mount attaches to) and the scope's front end. Obviously, this does not account for any weird shapes on the rifle.
 
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AtlMedic

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Unfortunately, the specs don't show the diameter of the front end of the scope.

The minimum thickness (at the center line) of appropriate bases would be 1/2 the diameter of the front end of the lens minus 1/2" plus a little clearance space. Do the calculations in decimal inches and then use a caliper to measure potential bases that you can find at a store.

For a demo, assume the front end of the lens is 1.75" in diameter. The minimum thickness of the bases should then be (((1.75/2) - .5)+.15) or 0=.525" assuming you wanted 0.15" clearance between the barrel (actually the surface the mount attaches to) and the scope's front end. Obviously, this does not account for any weird shapes on the rifle.
Thank you. I will do that method and the coin trick both so I can hopefully come up with roughly the same number.