Originally Posted by sdowney
If the scope is on a 20 MOA base, there is a substantial difference between the objective, midpoint, and ocular lens and the rifle bore. Where do you suppose I should take the measurement from?
I have 2 rifles with angled bases, one is 20moa, the other is 40moa. I measured from the center of the ocular to the center of the bolt on both of them and have had no problem with the drops matching the data from JBM & Exbal.
According to my calculations, there shouldn't be much difference between the front and the back with a 20moa base.
1 moa at 100yds (300') = 1.0472"
For a scope that is 1' long and 20moa base, there should only be approx .06981333" difference front to back.
20*1.0472/300 = .069813333" (inches subtension/ft for 20moa base)
You can measure the back and know you are within .1" of whichever number works best with your particular calculator.