If I had 1400 to spend on a scope, I would look at the NF NXS probably first. The 5.5x22x50 has the most moa, but depending on how for you want to shoot, you could get away with the more powerful but less moa versions and say a sloped base, if available for the ar-10. While 10x will work at 1,000yds, more power is better say 20x or even more. You are even in the low price range of the S&B scopes, some argue they are the best glass available, but NF's are hard to beat, and probably a best buy for the money. And there is always the Leupolds, Burris and others.
My personal fav. is the, www.Horusvision.com
scopes. Unique reticle system worth taking a look at, you could even get the reticle of your choice in a S&B, Leupold,... ect.
Interesting rifle/cal. setup. I have been pondering making an identical gun, be sure and post with updates.
Good shooting. [img]/ubbthreads/images/graemlins/grin.gif[/img]