Fundamentally, this is the mutt's nuts of all battle rifles. It combines ergonomic perfection, low recoil, high reliability, and frankly ridiculous levels of accuracy for something you're going to give to a Tom. The Portuguese version approaches 1 MOA accuracy with reasonable ammunition, often better than sniper rifles of its day.
The rifle is currently undergoing somewhat of a resurgence, with Armalite, Knight's, DPMS and others producing a huge range of battle/sporting/"Sniper" AR 10 variants under a variety of names. Even the Boxheads have got in on the act with the HK 417. The Canadians have adopted the AR 10 T as a semiautomatic "sniper" rifle, for use in certain long-distance target-rich environments which have been alleged to be sandy in nature.
[Stoat's Note: I am a very lucky man to own one of the original Portuguese contract AR 10s]