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Units of Angular Measurement for Optics

For Tactics, Techniques, and Procedures Thursday, we are continuing our discussion from last week about optics. Specifically, we are discussing how do we know if our projectile is going to hit a target at a certain distance? What is a way for a Paratrooper to know how accurate their weapon is? Or how accurate their shot group is? The Answers are in units of angular measurement.

There are two major units of angular measurement the Army uses: mils and Minutes of Angle (MOA). These two different units are commonly used terms to describe a measurement of accuracy when firing a weapon, system, or munition. They typically include the accuracy of a specific weapon, the performance of ammunition, and the ability of a shooter as it relates to firing the weapon.

Minute of Angle is a commonly used term to describe accuracy.  It may explain the accuracy of a weapon, performance of ammunition, ability of a shooter, or a combination of these aspects.

Minute of Angle (MOA) depends on size and range. It is an expression of an angle, so size will increase as range increases. A minute of angle is 1/60th of a degree (360 degrees) or 0.16667 degrees of arc. From any center point outward, this angle translates to 1.0476 inches wide at 100 meters and is stated as 1.047 inches at 100 meters. For ease of math, it is easier to say that 1inch= 1MOA at 100 yards, or 1.1 inches = 1MOA at 100 meters.  Picture two illustrates this for us.

Minute of angle is determined not only by the size of the group but also the range at which the group was fired.  For example, 2 inches at 200 yards is 1 MOA. 2 inches at 100 meters is 2 MOA. 1 inch at 200 meters is ½ or .5 MOA.

The other unit of angular measurement is the mil. It is commonly used in direct fire and indirect fire applications. Picture three illustrates the mil and how it relates to a more common unit of angular measure: the degree.

For every one mil, there are approximately 3.375 Minutes of Angle. For simplification of math, 1 mil = 3.5 MOA.

The Adjustments in the Common optics used by the Paratrooper are set up in Minutes of Angle with a few exceptions, those being the M145 Machine Gun Optic, and the Iron Sights on the Machine Guns. The other system that uses mils as both an adjustment and hold value are Sniper Optics.  For those reasons, it is important for Paratroopers to have an understanding of both systems of angular measure and not just MOA.

Where this really comes into play is when the Paratrooper conducts the Individual Weapons Basic table and zeroes the sighting system to their weapon, they need to know Minutes of Angle to be able to adjust their sight. The Zero and Grouping Target for the Army has been standardized to a one-Minute of Angle grid so that both optics and Iron sights can be adjusted on the same target with ease.

To sum up, There are two major units of angular measurement used for weapons: mils and MOA. Minute of angle is equal to 1.1 inch at 100 meters and is used as an expression of accuracy due to its expanding at a uniform rate. 1 degree is equal to 17.78 mils, and one Mil is equal to 3.375 Minutes of Angle. Minutes of Angle are used in the optics and Iron sights of the M4. Mils are used in the Optics and Iron sights of the Machine guns, and in the scopes and reticles of sniper rifles. Next week, we will continue our discussion on optics as we address the Primary Reflex Sight of the Army: the M68 CCO.

#Weaponsmastery #MilsandMOA

Raymond Miller
82nd Airborne Division Small Arms Master Gunner: primary weapons trainer, force modernization for individual weapons, and range liason for the 82nd.

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