Post #9711

More gun stuff.... very often when looking at scopes we hear terms like MOA or MILDOT. What are these? We all know that a circle can be divided into 360 degrees. But each degree can be subdivided into 60 minutes... and each minute can be further divided into seconds. When you hear GPS locations in Degrees Minutes Seconds, these are exacty these units... in the case of the earth, a degree is about 60 nautical miles, and minute of angle is 1 nautical mile (or 6076ft 1.15 statue miles). But when we scale this down to the distances we shoot at , a Minute of Angle (1/60th of a degree is nearly exactly 1inch at 100yards. So when you hear a gun guy say he's got a gun that shoots a a 3moa group, that means he can put 3 shots inside a 3 inch circle. When we zero a scope, you will see the windage (left right) and elevation (up down) adjustments are in 1/4moa clicks. That means that turning the elevation 1 click will move the bullet's impact point 1/4" at 100 yards. If you get really down into the weeds, you'll soon realize that a MOA isn't exactly 1 inch. that would be far too convenient. It's actually 1.047" at 100 yards.... So in guns we use the SMOA (shooter's MOA) where the MOA has been nudged a tiny bit to be 1 inch. When you look through a scope, you may see normal cross hairs or you may see cross hairs with dots on them. Those dots are MILDOT... yes they are metric. The actual measurement is called a milliradian MILRAD. Each of those dots is supposed to represent 10cm at 100meters.... 10cm is about 3.9" and 100 meters is 109yards.... so one mildot at 100yards is 3.6". Scopes have the cross hairs (reticle) as a first or 2nd focal plane. The vast majority of scopes that have a zoom lens are 2nd focal plane. The cross hairs stay the same size and the image gets bigger or smaller. There's only one zoom factor that makes those midots 3.6" apart.... usually 9x. To make it easier to figure out, many manufacturers put a white dot on the zoom ring to show the calibrated point for hte mildots. More expensive scopes are first focal plane. In these scopes the image and the reticle zoom together. For these it does not matter how zoomed in you are, the mildots always show 3.6". So here's the crazy part.... here in America we can buy a scope that uses MILDOT crosshairs and MOA windage and elevation. It would be like having a car speedometer that reads in MPH and the odometer reading in km. It is something that hte industry needs to fix. I've got a few >$1000 scopes that have windage and elevation in 1/10 MILRAD. This actually makes zeroing the rifle VERY easy.