20 MOA base height difference

[mshelton]

Anyone know with a 20MOA base what the ring to receiver height difference is between the 2 rings on something like a short action Panda or Bat (700 probably isn't a good example because of the non uniform receiver). I don't need the exact measurement, just a rough idea, like is it .040 difference or closer to .010.

I need to shim and bed the inside of some rings to get more travel in a rifle.

 

[expiper]

Mike,,,each .001 in dif. "usually" gives you 1 MOA of change,,,sooooo ,,to get 20 MOA it would take .020" shim in the rear,,,,(this is with 4-5" of ring spacing,,,,,Im shur others will correct my math ,,this is aprox. and EZ to remember,,,,hope this helps,,,,Roger

 

[mshelton]

That's perfect, thanks.

 

['Freak]

At one inch, one moa spans ~ .0002908882086656”, or rounded to a bit more reasonable be .000291” per inch. That times the rings’ spacing times however many moa gets the difference in height above the barrel’s bore center figgered at the rings. If the rings are spaced on 3.5” centers then the rear ring should stand .0204” higher than the front ring, or .000291 * 3.5 * 20 = .0204”, rounded. If the rail that the rings are mounted to is claimed to be a 20 moa rail having an overall length of 4.5”, then the back end of that rail should stand .0262” higher above the bore’s center than the front end, or .000291 * 4.5 * 20 = .0262”, rounded.

 

[Alexander-M]

Or use the following (a bit closer):

20 MOA = 20/60 = 0.3333°
Tangent of 0.3333° = 0.00581

Multiply 0.00581 times the distance between the rings.

Examples -
Four inches between the rings: 0.00581 x 4 = 0.023 inches
Six inches between the rings: 0.00581 x 6 = 0.348 inches
100 yards: 0.00581 x 3600 = 20.916 inches (which would make 1 MOA 'close to' 1.0458; actually 1.047)

Nando

OOPS! I just read the post by Olefreak - - - still, both yield about the same results.

 

['Freak]

My moa figgerin’ begins with mashing the key on my cheap TI-30XIIS calculator what returns the value of Pi, or 3.14159265359, which divided by 3 so happens to also equal inches spanned by 1 moa at 100 yards, or 1.047197551196”.

 

[mshelton]

Thanks for the detailed math guys, nice to have that filed away.

OleFreak, I used to eat at Cafe Ole, they were good but under new management now and I don't eat there any more as they are no longer good.