I get a great enjoyment out of over-thinking this stuff. Between working out and load development, what else am I going to do between hunting seasons??? 
I've used the black sharpie method and yes it works well. The main goal with this effort is to use the comparators to measure off the bullet shoulder junction instead of the meplat. So I'll get back after it...time to see how the ELD-X do in the 264WM.
Thanks for the input guys. Shoot straight and shoot often.
Darn! The whole time I thought the damn Sharpie was giving me my base measurement to the ogive.
