What is Milliradian (MIL)?

Milliradian (MIL) is a unit of angular measurement often used in the context of shooting and ballistics to describe the accuracy of firearms, scopes, and shot groupings. One MIL is equal to 1/1000th of a radian, and at a distance of 100 meters, it subtends approximately 10 centimeters (3.94 inches). MIL-based systems are commonly used in applications where metric measurements are preferred or more familiar.

Understanding Milliradian

The concept of MIL is used to quantify and communicate various aspects of shooting performance:

• Firearm Accuracy: The inherent accuracy of a firearm can be described in MIL, representing the expected shot dispersion at a specific distance. For example, a rifle with an accuracy of 0.5 MIL is expected to produce shot groupings within a 5-centimeter diameter circle at 100 meters, 10 centimeters at 200 meters, and so on.
• Scope Adjustments: Scope turrets have click adjustments measured in MIL or fractions of MIL (e.g., 0.1 MIL per click). These adjustments allow shooters to make precise changes to their point of aim using the metric system.
• Shot Groupings: MIL is used to describe the size of shot groupings, indicating how closely together shots land on a target at a given distance. Smaller MIL values represent tighter groupings and better shooting performance.

Calculating MIL

To calculate MIL, the following formula can be used:

MIL = (Group size in centimeters / Distance in meters) x 10

For example, if a 3-shot group measures 7.5 centimeters center-to-center at 100 meters:

MIL = (7.5 / 100) x 10 = 0.75 MIL

MIL vs. MOA

Another angular measurement used in shooting and ballistics is the Minute of Angle (MOA). MOA is equal to 1/60th of a degree and, at a distance of 100 yards, subtends approximately 1.047 inches. Both MOA and MIL are used in scopes, reticles, and ballistic calculations, and the choice between the two depends on personal preference, familiarity, and desired level of precision.

Key aspects of MOA in comparison to MIL include:

• Scope Adjustments: Similar to MIL, scope turrets can have click adjustments measured in MOA or fractions of MOA (e.g., 1/4 MOA per click). These adjustments allow shooters to make precise changes to their point of aim in a consistent, quantifiable manner.
• Reticles: MOA-based reticles are available for shooters who prefer working with the imperial system, offering a consistent method for measuring and adjusting for windage and elevation.
• Precision: While both MOA and MIL can provide precise measurements and adjustments, the choice between them depends on personal preference, familiarity, and the desired level of precision. Some shooters find it easier to work with MOA due to its direct relationship with the imperial system.

References

• Cleckner, R. (2016). Long Range Shooting Handbook: A Beginner's Guide to Precision Rifle Shooting. CreateSpace Independent Publishing Platform.
• Litz, B. (2011). Applied Ballistics for Long Range Shooting. Applied Ballistics LLC.
• Barsness, J. (2006). The Big Book of Ballistics. Skyhorse Publishing.