I was in the market for a longer range, varmint-type scope for my .204 prairie dog rifle this past spring. Another member of the forum here, Big Red Fox, tipped me on that Burris E1 scope. He was using it on a .223 AR and it worked fine. So I decided to give it a try on my .204. What you do is, you send Burris all the info about the rifle/caliber your're shooting--bullet weight, BC, muzzle velocity, zeroing distance, sight height, etc. and they put it into their ballistics calculator. Then they'll send you the printout which tells you what distance each of the "hash" marks corresponds to.
Anyway, the scope works great for me, I especially like the windage indicators/marks in the etched, "Christmas tree" reticle. It's very clear, and optically excellent, especially for the price. I liked it so much that a couple weeks ago I bought another one, this one to go on my 6BR rifle. I'll shoot it tomorrow for the first time.
If you decide to get one of these, PM me and I'll give you info on where I purchased mine recently, at a great price.