Research it online and see it's benefits over 5.56/.223 in urban parameters.
For battle-grade toughness, go with:
Noveske (pricey but afghanistan-grade ironclad)
Palmetto State Armory
Not to hijack a thread but I have been thinking about getting a AR-10 .308 type for hunting and also just to have one. Do all the same recommendations also fit? I was looking at the Remington R-25.