All the "brochure-int" you wanted to know about the gun as far as specs are concerned are here:
http://larueosr.com/
We used Hornady match grade ammunition from BulkAmmo.com for our evaluations. Check them out, they have a wide selection of ammunition at competitive prices.
Some of the wave top points to be made about the 7.62 (.308 depending on your background) OBR are that it is obviously a more powerful round that your M-4s 5.56 (.223 depending on your background). The M-4 carbine is really designed to be a 200 meter gun, but with the LaRue Tactical OBR, coupled with some training, you could be hitting steel hard at 800 meters and beyond. The OBR isn't just a sniper rifle. If you opt for a shorter barrel (we like the 18) and collapsible stock and 1-4x optic, you could very effectively use the rifle for short range work as well.
Warning: This isn't an M-4, it's heavy. Be ready.
We at STT highly recommend you round out your firearms collection with a battle rifle. Which one is up to you. We obviously recommend LaRue Tactical.
Stack it Deep!