[Jeff Higgins]

What kind of an air rifle? Spring piston, pre-charged pneumatic, pump-up pneumatic, what? What caliber? What weight pellet will you use? This makes a difference. For example, "springers" are notoriously hold sensitive because the vibrate so much while the pellet is traveling down the bore. The other platforms have their inherent issues as well.

As far as mil dot usage, most only "work" at a given power setting. This is the important part, though - they are not meant for hold-over or windage correction. They are meant for range estimation on targets of known size. Once you have determined the range and/or the wind value you are dealing with, you make the necessary corrections with the scope turrets so that you still hold center.

There are scopes available with secondary aiming points tailored to a specific cartridge firing a specific bullet at a specific velocity. Typically the crosshairs are used as the 200 yard aiming point, and a series of dots below it represent point of impact at various yardages. I doubt these are available tailored to air rifles, though.

So much for the intended uses of all of this stuff. That's all well and good, but you can still mount such a scope on your air rifle (or any rifle for that matter) and learn to use them as you wish. One of the best applications I've found is a Weaver "muzzle loader" scope. It has "trajectory compensating" dots below the crosshair intersection. Through much trial and error, I've learned where the rifle that wears it hits at various ranges. Works great.