A milliradian (often abbreviated as mrad or mil) is an angular measurement unit commonly used in firearms applications for adjusting sights and calculating bullet drop. One milliradian subtends an arc of one thousandth of the radius of a circle. At a distance of 100 yards, this angle corresponds to a linear measurement of approximately 3.6 inches. This allows for precise adjustments to sighting systems, particularly for long-range shooting.
Utilizing this angular measurement offers several advantages. It provides a consistent and mathematically sound basis for adjustments, regardless of the specific caliber or rifle being used. This standardization simplifies the process of zeroing a rifle and making adjustments for different ranges and environmental conditions. Historically, this system has been widely adopted by military and competitive shooters for its precision and ease of use. Its adoption has significantly improved long-range accuracy and consistency.