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.

Optimum Point Blank Zero

by Harley Ayre

Want to get maximum usefulness out of your airgun with minimum aiming hassle? Here's a concept that is extremely useful: Optimum Point Blank Zero.

What is Optimum Point Blank Zero? It's the fine art of zeroing your air rifle or air pistol at the range that will give you the greatest span of ranges at which a directly aimed shot will produce a point of impact close enough to "get the job done." Getting the job done, of course, might involving knocking down a field target, taking small game, or something else.

So, for example, suppose you have an air rifle that launches pellets at 820 fps and the sight height is 1.5 inches (from the center of the sight to the center of the bore), and you decide that it will be acceptable if your pellets land within a .25-inch radius of your aiming point . . . then if you zero your sights at 33.2 yards, all shots from 11.2 yards to 36.9 yards will land within a quarter-inch of point blank if you are shooting correctly. That's a range of 25 yards where all you have to do is point and shoot. Is that cool, or what?

As they say in the infomercials: "But wait, there's more!" Suppose you decide that it would be satisfactory if your shots landed within a half-inch radius of your point of aim. If you zero at 38.6 yards, you get a range of 34.4 yards (from 7.5 to 43.9 yards) in which you can point and shoot.

Now, I can almost guess what you're thinking: "Optimium Point Blank Zero sounds great, but how am I going to figure it out for my rig?" The short answers: you don't have to! Just go to www.airgunexpo.com/calc/calc_opbz.cfm, and you’ll find a neat online calculator, devised by Steve in NC, that will figure it out for you. Just plug in the sight height, muzzle velocity, and vital zone radius, push the CALCULATE button, and it will produce a chart that tells you what you need to know.

There is also a very slick online demo of Optimum Point Blank Zero at www.arld1.com/trajectorypbr2.html. There you can play with different variables (sight height, vital zone radius, muzzle velocity and ballistic coefficient) to see how they have an effect on the point blank range.

Optimum Point Blank Zero is a very powerful concept. Once your airgun is set up for it, it’s a tremendous confidence builder and aid to shooting more accurately.