Mil Dot range Table
I have now read three separate articles on the Mil Dot, minute of angle, and the non-existent difference between Army and Marine Mils.
First what is a mil? It is a shorten name for a milradian. That is it is 1/1000th of a radian. So, what is a radian? "A radian is an angular measurement that is equal to the angle formed at the center of a circle by two radii cutting off an arc whose length is equal to the radius." That is a direct quote from the Webster's New World Edition Dictionary. Look at it as a slice of pie in which the "outer rounded side" is equal to the two straight sides. The angle at the pointy end is one radian. How do you find this great angle? OK, radian = 2 pi r/r is the standard formula. So a circle with a five inch radius becomes (2 * 3.1416 * 5)/5 = 6.2832 radians to a circle of 360 degrees. By dividing 360 degrees by 6.2832, you find that there are 57.2956 degrees in a radian. You also know that there are 6283.2 milradian in a circle. Either of these can give you the number of minutes of angle in a milradian or mil. That magic number is 3.438, which is commonly rounded to 3.44. This is a mil is a mil is a mil. There is no difference in Marine or Army mils. The problem is the military compass.
The military compass is marked to show 6400 mils in a circle. The reason behind this I do not know for sure but have been told by numerous sources that is was easier to mark off compasses in 6400 than in 6283. This is also the source of the myth that the Russians use different mils then the US. Their compasses are marked with a different number of mils in a circle. However, again a mil is a mil. It is based on a set mathematical formula that was used by the scope manufacturers in their marking of the reticles. Leupold marked their mils as mils. There are 3.44 moa in a mil. There are no Army and Marine mils. There are only mils.
There are differences in the mil dots however. The Marine mil dot is stamped on wire and the dot is 1/4 mil length or longwise. The Army dot is etched on glass and is 3/4 of a minute of angle or .22 mil. While the Marine dot can be easily broken down into 1/8th increments the Army dot can be easily broken down into 1/10 increments. This is very accurate and breaking the mils smaller then 1/8 or 1/10, when ranging with mils, is asking for a disaster and a miss at longer ranges. The mils are easily broken down to 1/4 mil increments for leads, wind calls, and holds for elevation or missed shot correction. None of our students have had any real problems with misidentification of 1/4 and 3/4 mil increments. It is called training.
While I do not know how all of the scope manufacturers make their mil dots, I do know that all of the scope manufacturers do know what a mil equals. I would be very cautious with the table shown on one of the articles purporting that some are "Army" dots and others are "Marine" dots. The biggest problem in the Mil Dot arena is the introduction of myth verses reality. Such as the great 3/4 mil, mil dot of John Plaster.
8-26 in. x 50 mm Benchmark Scope
Lawn & Patio (BARSKA)