What I put is 100% accurate. This is how I was taught and how it's still being taught. Get your scope out and put a target up, measure it, pull your scope out and mil it, then if you have a rangefinder, hit it with your rangefinder and it will be within 1-2 yards, or meters depending on what formula you use..
I was a Designated Marksman in the Army and this is how I was taught.
I'm going to a sniper course in May, so I'm sure I'll be able to elaborate more then. Steve Reichert, James Gilliand, and Rob Furlong are teaching the course... btw