Recently I explained my new thinking on ranges to sight in my BLK. However targets can appear at many different ranges and this is not a new problem relegated to the 300 Blackout. While BLK- specific optics feature dual reticles to help range different shots with subsonic and supersonic ammo, other systems exist and have been used with great success for many years.
The three common methods to correct for trajectory and/or wind on a shot outside your zero range are adjusting in inches, Mils or MOA. Inches are a system used in countless other applications so we won’t cover that method any further. But how can we simply define the other methods?
MOA stands for Minute of Angle. Imagine you divided a circle into 60 equal parts- like minutes on a clock. Except 1MOA is 1/60th of a degree. While that may seem complex the units make the system extremely user-friendly because at 100 yds 1 MOA always = 1.047″. In practical use that equates to 1″ per 100yds no matter what caliber or what distance. Knowing how many MOA per click you have on an optic, along with range of target is pretty much all you need to know for MOA.
MILs are a little different. The name is short for mili-radians: one thousandth of the distance to an object. Simply put, Mils allow the user to estimate the range to a target based on the size of the object (height/width) in the reticle. A MIL reticle has many dots on each axis that are used to accomplish this – sometimes referred to as MIL-dots. As you can see from the picture below this method is really clever but also requires strong mathematics or use of a reference chart/tool.
To use a mil-dot reticle effectively, all one need remember is that the distance between dot centers is 36″ at 1000 yards. This lets you determine the range of a target of known size. At that point, you can dial the scope in for proper elevation OR use the dots to hold over the proper amount. The dots on the horizontal crosshair can be used to lead a target (if you know the range to the target, then you’ll know the distance between dots, and thus the distance to lead) or to compensate for deflection.
Converting between the two systems is not a very clean exercise- check out the conversions noted in this image:
For that reason I think each user can choose between one system or the other. Watch this space for more on choosing the right optics for this- especially as it pertains to the BLK.