a. I have a 5 - 20 power scope that the reticle scales in moa at 20 power. It is a second focal plane scope.

b. There are 3.38 moa to a mil.

c. 20/3.38 = 5.917...

So,if I set the scope on 6 power minus a smidge, would it be reasonable to assume that the reticle will scale in ± mils at that power setting?

Does the manufacturer's info state at what power the reticle subtensions are correct? On an SFP scope, the subtensions will be "on" at the power the manufacturer sets - usually the highest.

As with any scope though, making a dope card removes all doubt.

Doug Mann

I've been told by a former USMC sniper that 10X is the usual setting that they're "on".

I'll check it on the range against a Mil scope.

I was just curious if anyone knows if theory behind the math works in real life.

The math works as far as the numbers go - the problems or deviations will come from an imprecise reticle, subtensions which are a tad off, magnification not being EXACTLY 20 times actual size, and human perception. As long as you have a known distance range and targets of a precise size to check the subtensions, you can verify and make a good range/dope card for that rifle and load. If you don't already have a Mil Dot Master, get one and you don't have to worry about being able to input a bunch of data in your iPhone ballistics App: http://swfa.com/Mil-Dot-Master-P91.aspx

Batteries can always die in a Laser rangefinder. Knowing how to range with a good reticle is a good skill to have.

Doug Mann

I bought one of the Sig Kilo 2000 range finders.
From the porch of the showroom, it quickly ranged a billboard at 713 meters. That's as far as I could see due to terrain and the highway turns.
The reticle I am referring to is a Nightforce MOAR in a 5-20 SHV on a Rem 700 LR in 30-06. Also put a Bartlein 5r Rem Varmint weight cut to 20 inches and chambered 30-06 in a Mauser Mark X action I had.

Doug email me please at MRoberts53 at AOL dot com.
It's an old email but still works.