Is there a rule of thimb to calculate how much slope to machine into a scope base to achieve 20 minutes? I'ev got a flat rail for a Musgrave, and a friend has offered to grind a slope into it, but we're both wondering what the calculation is. I guess I could check w/ shims, but does anybody know off hand?
calculating angle for 20 moa scope base
- Thread starter mpwolf
- Start date
Its not much. About five and a half thou for every inch of the length of the base.
20ma = approx 20 inches at 100 yards
or 20 inches at 3600 inches
20/3600=.0055 rise per inch
someone smart check my math. so if the base is 4 inches long, you would machine it down .022 of an inch over its length
20ma = approx 20 inches at 100 yards
or 20 inches at 3600 inches
20/3600=.0055 rise per inch
someone smart check my math. so if the base is 4 inches long, you would machine it down .022 of an inch over its length
correction X base length
------------------------
Range in inches
20 X 4 divided by 3600 = .0222" Strictly speaking this is for 20 inches at 100 yards, not 20 MOA. Close enough? Or you could go .33333333333 (Sine) x 4 = .0233"
------------------------
Range in inches
20 X 4 divided by 3600 = .0222" Strictly speaking this is for 20 inches at 100 yards, not 20 MOA. Close enough? Or you could go .33333333333 (Sine) x 4 = .0233"
Last edited:
treebutcher
CGN frequent flyer
- Location
- Nova Scotia
Dogleg is right on the money
What I have done in the past is rap the receiver with a piece of #14 common copper house wiring under the furthers back portion of the mount then used DEVCON to fill in the ‘wedge’. Make sure you use a release agent! Black shoe polish works better than anything else I have tried. Also, I have found that for every one thousand of an inch under the rear of the base, my point of impact at 100yards changes about 1 MOA or 1 inch. Good luck with your experiment!
Thanks gents. This I know this is not the cost effective, or easy way to go about this, but It seems like an interesting experiment, and I think my only real option. The rifles we're discussing are my F/Tr gun and a second rifle I'm trying to set up as a backup.
I'd go w/ the Burris rings in a heartbeat, but the rifle in question is a backup rifle, and I can't afford a second scope. I'm trying to be able to slide the scope and rings off #1 rifle, and slide them onto #2. Because #1 rifle has a built in sloped rail, and there isn't enough adjustment in the NF BR to make it to 900m w/o shimming, sloping rail #2 seems like my best alternative.
I'd go w/ the Burris rings in a heartbeat, but the rifle in question is a backup rifle, and I can't afford a second scope. I'm trying to be able to slide the scope and rings off #1 rifle, and slide them onto #2. Because #1 rifle has a built in sloped rail, and there isn't enough adjustment in the NF BR to make it to 900m w/o shimming, sloping rail #2 seems like my best alternative.
