Need one for a 5.52 and another for a 7.62 AR.

Viking Tactics or Blue Force Gear. Both of their slings are great.

Those two, and maybe the new D3, are probably the top choices to find the best sling for you. But, all three are different, and whereas one may find the VCAS to be perfection and the VTAC to be unworkable, another may find the complete opposite to be true.

I like the MagPul MS3. It can be used as a single point or a two point. You can get it in clip/clip or clip/single point configuration. It converts in seconds, simply unclip it fro the single point ring and it's a two point. It adjusts simply and quickly for length and it's built stout.

Another vote for the VTAC.

Ed

I've had all three mentioned so far and all are great. I prefer the Blue Force Gear Vickers without padding for lighter weight guns. For about 9 lbs. or more loaded I opt for the padded version. I put TriGlides on some but find I run as a two point 99.9% of the time. I like plastic over steel adjusters.

http://www.wayofthegun.us/black-proctor-sling/

I bought two of the Proctor slings and mounted one on a 16" A-1 style carbine with triangular handguards because it was lightweight and fixed my mounting problems. I tried to like it because I was sold on it in principle and it is about the lightest adjustable you can find. It hasn't worked out that way though and the second sling remains unused at least for now. Texture just seems a little too slick to me. Others may not be bothered by this. Still I consider it a good product and eliminates the need for aftermarket sling mounts. Maybe I've been spoiled by the Vickers.

I had the same thoughts on the proctor sling. It's nice if you need a sling and don't have mounting hardware. Otherwise, the VTAC and Vickers seem to be better overall.