SD is standard deviation, you need to find someone with a chrono and preferably some long range reloading experience to give you a hand with your load development.
You don't need a Labradar just a inexpensive optical will do. I am using a sub $100 Pro Chrono and am getting good results at the target. Invest in some of Bryan Litzs books and do a search for Erik Cortinas 100 yard load development thread at Accurate Shooter.
I have never had the opportunity to shoot beyond 800 myself. I want to some day and good luck to you.
Ah, gotcha on the SD thing.
I have Litz's, "Applied Ballistics for Long Range Shooting," about a third of the way through now.
I'd like to get a chrono, the MagnetoSpeed looks interesting, but alas, right now it's just not in the budget. Heck right now I only have a budget for two, maybe three more test ladders, then I have to choose a recipe and hope for the best.
I have been pestering a buddy of mine that has some experience with long range target shooting/reloading, but our schedules aren't simpatico, so mostly to this point I'm going solo.
However, in my favor, I've been told that only a few targets will be beyond 800 yards so I'm fairly confident that if I can find a cartridge that performs well at 500-600 yards, I
probably won't make a fool of myself.
Anyway, thanks for all the help people, hopefully I'll have another update in a week or so. With any luck I'll have narrowed things down to two or three prospects by then.