What size rings are you using for a 3-9x40 scope and still keep a good cheek weld?

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Gun control means two hands

dont go by "low, medium, or high" but see this method.

With a little math this is the perfect way to do it


Take the outside diameter of your scope's objective, then divide that by two.
Scope has an O.D. of 50mm. 50/2=25mm (.98")
or an OD of 40mm, 40/2 = 20mm (.78'').

This will be the dimension above which the ring and bases combined will need to raise the scope's centerline to clear a barrel that is the same diameter as the action..

Once you have that key dimension, all you need to do is select a base and ring combination that equals that dimension plus 3mm-5mm to accommodate lens covers.
25mm+3mm=28mm (1.10")
20mm+3mm=23mm (.90'')


Now you need rings which will take up the rest of the dimension. This is where you need to pay attention because this is where most of the confusion and inconsistencies come from. Manufacturer's ring heights are not uniform from brand to brand, IE: Burris' low is not the same as Leupold's low. Ignore their descriptions and go by the actual measurement of the ring. Usually found on their website. The actual measurement of "ring height" is determined two different ways. Some measure from the top of the base (where the ring contacts it) to the centerline of the ring (Fig. A). If you have Figure A you are done, just compare it to the number calculated earlier, you want it to be just a bit more than this number for clearance. Others measure from the top of the base to where the ring first contacts the scope (Fig. B).

If the brand you are considering measures their ring height like Fig. B, you will need to add 12.7mm for a one inch scope and 15mm for 30mm scopes to get to the centerline of the ring. Add the number to the B. Figure given. you can use google.com and type in the search bar for example ".60in+12.7mm to in", as a quick easy calculator. Once again make sure the ring is ever so slightly higher than your previously calculated number. (ie. with a measurement of 23mm or .90'', don't get .890'' rings.)

Not sure what scope you're considering but it's easy to measure the distance from the rail to the center of the rear sight aperture. As the center of the scope gets higher than that number you start to need a giraffe neck, or a stock riser.

-- Chuck