Family Guy thoughts on the 6.8spc
If you don't plan to shoot over 1,000 rounds per year, but you want an AR-15 for general purpose, this is the cartridge for you. The 6.8spc is hands-down the best AR-15, even better than the 5.56. I got into the AR platform a few years ago and looked forward to teaching my kids with it. Now that I have a 6.8 and understand what it can do, the 5.56 makes less sense. We train with BB guns and .22s and of course dryfiring. As they get older, I plan to train with Airsoft, force-on-force. None of that will change (due to economics or politics) whether we have 5.56s or 6.8s.
I've shopped like crazy, looking for good 5.56 hunting ammo. Black Hills 69 grain OTM and Hornady T2 will cost 75 cents to a dollar per round. Not much different from 90 grain 6.8spc which walks all over it, for any purpose I'll have. Cheap brass 5.56 ammo is minimum 50 cents around, so not much savings. I love p-mags and hope something like that will come along for the 6.8, but I don't lose sleep over that. I think we'll find the new 6.8s to be just as reliable as 5.56s, predominantly due to the work by Constructor and Tim leading up to the Xtreme upper (get one!)
So if you get confused or discouraged reading about people arguing about the 5.56 or Grendel being better choices, spend some more time reading other threads on this site. If you're worried about cost and availability of ammo, so are all the gun guys, regardless of caliber. Whatever AR you decide on, plan on buying at least 1,000 rounds, and adding to that number as you can afford it. If politics go to heck, just cut back a little...like everyone else.