MOA rails, shimming.. formula?

[ultimate_monkey]

I know iv seen it befor but like i can find it! the formula / math for shiiming scope rails..

like how many thou per inch to get what MOA.. like if say 20 MOA is 5tho per inch (yea i know its not) and my scop rail was 5" long from mounting screw to screw id need to shim the rear 25thou.. etc and so on

any one have a grid that shows the corilation or any thing?


i hope im makeing sense, my brain to screen doesnt always jive haha

thanks

 

[Obtunded]

depends how long the rail is.

 

[ultimate_monkey]

would it not be irelivant? a longer rail needs overal more thickness change then a short rail, but a short rail still is on the same angle...

useing 1/1000 per inch for MOA X, a 5" rail needs 5thou increase between the 2 mounitng points , and 10" 10 thou and so on, it wouldnt change the angle the that rails sit on..

 

[redshooter]

It's just a ratio so I think it goes like this.

MOA(in inches)/3600" = hight to shim/Length of rail (distance from low END to high mounting point in inches)

Which becomes MOA (in inches) X length of rail (in inches)/3600" = hight to shim.

So if I'm right and say you want to shim 10 MOA and the rail is 6" from the end to the screw you want to shim the equation should be.

10"x6"/3600"= 0.0166667" assuming 10 MOA at 100 yds

It wouldn't be screw to screw it would be from the lowest point to the screw you want to shim the most. Wouldn't you also need to shim the other screw as well? A very tiny amount

 

[Juster]

Moa is aboot 1" at 95.5 yards, 1" at 3438 inch, so 1 Moa = 1/3438" for rings an inch apart, 2/3438" for 2 inches apart.

 

[ultimate_monkey]

thanks Redshooter! that would be what i was looking for, haha.. i knew it was relitivly simple but math isnt my strongest point..

and id be better off to bed the front of the rail rather then shim it shimming the front doesnt give 100 % contact.

that being said im doing this for my 22 haha


thanks as well juster!

 

[redshooter]

No prob. I dug up my math text from college and was looking over trig. Then I realized it's just a ratio...much easier.

 

[redshooter]

Hmm...So to shim a rail you could use a spacer to get your height and then use some type of bedding compound to fill the space bettween the rail and the receiver?

 

[ultimate_monkey]

yup!

is ideal.. no not really, but in a pinch it works, especially if ur cheap like me haha.