What is Minute of Angle (MOA)?
What is Minute of Angle (MOA)?
Minute of Angle (MOA) 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 MOA is equal to 1/60th of a degree and, at a distance of 100 yards, subtends approximately 1.047 inches. In practical applications, MOA is often rounded down to 1 inch per 100 yards for simplicity.
Understanding Minute of Angle
The concept of MOA is used to quantify and communicate various aspects of shooting performance:
- Firearm Accuracy: The inherent accuracy of a firearm can be described in MOA, representing the expected shot dispersion at a specific distance. For example, a rifle with an accuracy of 1 MOA is expected to produce shot groupings within a 1-inch diameter circle at 100 yards, 2 inches at 200 yards, and so on.
- Scope Adjustments: Scope turrets often 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.
- Shot Groupings: MOA is used to describe the size of shot groupings, indicating how closely together shots land on a target at a given distance. Smaller MOA values represent tighter groupings and better shooting performance.
To calculate MOA, the following formula can be used:
MOA = (Group size in inches / Distance in yards) x 95.5
For example, if a 3-shot group measures 1.5 inches center-to-center at 100 yards:
MOA = (1.5 / 100) x 95.5 = 1.5 MOA
MOA vs. MIL
Another angular measurement used in shooting and ballistics is the milliradian (MIL). MIL is a metric-based unit equal to 1/1000th of a radian and, at a distance of 100 meters, subtends approximately 10 centimeters (3.94 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.
MIL: A Comparison to MOA
Milliradian (MIL) is another angular measurement used in the context of shooting and ballistics as an alternative to MOA. 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 often preferred in applications where metric measurements are more common or desired.
Key aspects of MIL in comparison to MOA include:
- Scope Adjustments: Similar to MOA, scope turrets can 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.
- Reticles: MIL-based reticles are available for shooters who prefer working with the metric 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 MIL due to its direct relationship with the metric system.
In summary, both MOA and MIL are essential tools for shooters; the choice between the two depends on individual preferences and familiarity with either system.