Do you want an AR with moderate recoil but an effective range comparable to that of .308? I learned recently that that is not a pipe dream. What you’re looking for is the 6.5 Grendel.
Based on the highly accurate 6PPC, the 6.5 Grendel lets you use heavier (but shorter) 140 grain 6.5mm bullets in a cartridge that fits in an AR-15 magazine. Its ballistic coefficient is comparable to .308, and the bullets supposedly stay supersonic out to 1000 yards and beyond to offer less wind drift and drop, as well as better terminal ballistics than .223 or 6.8 SPC (there are some nice graphs over on 65grendel.com).
So what’s the catch? For one, adoption of the 6.5 Grendel cartridge is still very limited, possibly because the designer, Bill Alexander, owns the cartridge. The name “6.5 Grendel” appears to be trade marked, and it appears manufacturers need a license to create parts and rifles chambered for the cartridge.
Nonetheless, a number of affordable AR uppers are available from Alexander Arms, as well as slightly less affordable ones from Les Baer, and they should work with any 5.56 AR lower. For those who prefer Minis, ASI also sells them chambered for the 6.5 Grendel. As for ammo, Alexander Arms sells quality loaded ammo, and cheaper Wolf ammo is available for plinking (ammoman has it on sale right now at $250/500). Of course, for hand loaders, dies, brass, and bullets are available as well. To top it off, there’s a fairly active forum for everything to do with 6.5 Grendel, and if you’re lucky, Bill Alexander himself may even answer your questions (now imagine having that kind of access to Eugene Stoner or John Garand…).
So… I think I know what my next AR project is going to be. Hell, it won’t even be a project. I’ll just get an upper and drop it in my existing lower. Gotta love modular designs 
