As part of my shooting projects I am trying to learn how to use a scope. There are a number of details that need to be attended to if you are to get all that is available out of it. The particular scope I have is the Burris 3-12X32. It is a very nice scope.

One thing about shooting is that you need to understand ballistics. Once the bullet leaves the barrel it is on its own. It has an initial velocity (a vector consisting of speed and direction) which is immediately acted upon by gravity and air resistance. These forces slow the bullet down and pull it toward the center fo the earth. It is a curved path which can be calculated by knowing the characteristics of the bullet (well documented many places) and the muzzle velocity. Now that I have my chronograph, I can measure the velocity and VOILA I have all the data I need.

The Burris Company has a few resources which are helpful. The reticle on the scope has a cross hair and some markings below it. You can use them for Bullet Drop Compensation( BDC). That is, knowing how high to aim as the distance to the target increases. Remember, the bullet is curving earthward during its flight to the target. The deviation from the straight flight patch can be measured in Minutes of Angle (MOA) among other things. If your ballistic calculations tell you that the bullet is going to be 12 inches below the sight line at 200 yards, you know that calculates to roughly 6 MOA and there you have your (simplified) sighting solution. Snipers and competitive long range shooters do a lot more calculations including temperature, air density, angle of launch and winds.

The problem I ran into was that Burris publishes all this crap about assigning distance values to the BDC points on the reticle. It is complicated. It requires you do mental math to interpolate the hold for a certain range. You calculate all this stuff for various loads and make a little table. Their user guide was just about useless to me. All I wanted was the MOA values at low and high power. You need both because this is a rear focal plane scope which means the reticle doesn't change size when you zoom the power. After a few calculations I came up with the attached diagram which I taped inside my ammunition box. I also taped in the ballistic table for the current load I am using. Pick the MOA drop off the little chart, check the reticle diagram and blast away. Can't wait to get out to the range again.