Setting up a Mil-Dot Scope

by Harley Ayre

Compared to most firearms, airguns shoot loopy trajectories. For example, an air rifle shooting 820 fps, with a sight height of 1.5 inches, and zeroed at 15.5 yards, will show a pellet drop of nearly two inches at 50 yards, 2.74 inches at 55 yards, 4.2 inches at 60 yards, and so forth.

So what's the best way of putting a pellet that follows a loopy trajectory in the kill zone at an unknown range? Field target shooters manage the trick by using a high-magnification scope with adjustable objective. The shooter focuses the scope precisely on the target and reads the distance to the target off the bell of the scope. Using that information, the shooter then adjusts the elevation knob of the scope to compensate for the rise or drop in the pellet at that exact range.

The problem with the range-find-with-the-scope/knob-adjustment system -- other than it can be very time-intensive to get it set up well -- is that it can be completely defeated by simply returning the elevation knob to zero in the wrong direction. It's really, really annoying when it happens, and all of your subsequent shots will be off until you figure out what happened.

But there is a way to get the job done while avoiding knob-twisting: by using a mil-dot scope. The mil-dot reticle scope was originally designed for the military to allow snipers to estimate the range more accurately. What makes the mil-dot reticle so useful to airgunners is that the crosshairs, plus the dots above and below the crosshairs, give you multiple different elevation aiming points that you can use to compensate for the trajectory at a given range.

It's easy to adapt the mil-dot reticle for use with an airgun. Start by zeroing the scope on the crosshairs at the zero range you prefer; say 20 yards (see the blog on Optimum Point Blank Zero). Once you are satisfied that the pellets are hitting where they should, move to 15 yards and trigger another shot, using the same point of aim. Now look through the scope again, carefully centered the crosshairs on your original point of aim. You'll see that the pellet shot from 15 yards has landed between the crosshairs and one of the mil-dots above or below the crosshairs. This is your new point of aim for 15 yards. Mark the 15-yard aim point on a picture of a mil-dot reticle (you can print one off the Internet or draw one by hand). Repeat the process at 5 yard intervals, and soon you will have mapped out all the points of aim for the distances you plan to shoot at. If you have a variable-power scope, be sure to use the scope at the same power at which you mapped your aiming points. Otherwise, you may miss because the relative distance between dots changes with the magnification on most mil-dot scopes.

To put the mil-dot to use in a practical situation, all you need to know is the range to the target (To find that, you can estimate the range, use your scope to range-find, or ping the target with a laser range-finder). Next, look at your chart to see which aiming point you use for that range, and you're good to go. It's just that easy.