Member Molon pic and quote; "The barrel on the Colt 6721 is the most accurate "off the shelf" chrome-lined, NATO chambered AR-15 barrel that I've tested."
FYI, whoever Molon is, he is known (and very highly respected) on every reputable "AR site" out there. I have read his posts in over half a dozen places. He is mainly known for very thorough testing of various AR platforms, barrels, and 5.56 loads.
In short, he knows his stuff.
I'm not planting my flag on "1/9 Mountain", but it is what it is. I wanted a heavy-barreled AR for my own reasons. The 6721 fits the bill. It comes with a 1/9 barrel. And both of my 1/9 barrels are sub-MOA accurate (from a bench) with the IMI 69 grain SMK loads. I'm not going to waste the money or time seeing if it will handle the 77 grain SMK's; there's no need. I don't hunt (anymore); compete; or sit naked in my closet with my AR's (anymore). I have them for one purpose and one purpose only: Win the fight. To that end, I have the 55 TAP for in-house; the 62 SBCT (TBBC) for anything out to 100 yards; and the 69 SMK's for anything further out. And I have a couple...three...maybe four, I dunno...thousand rounds of good old 55 FMJ for the Zombies.
Yes, I could have spent a ton more and gotten a more accurate rifle(s). But for what I spent, including the add-ons that GV so wisely guided me through, I'll stack my (hang on, doing the math)...$1600 rifle up against anything in it's price range. Besides, you'd shoot it better than I do anyway.
Then again, I'm an old school .45 ACP guy. Preferably a 1911 frame, although I did swallow my pride and buy a Glock. Nothing against the 9mm. Modern ballistics have closed the gap. But a 230 FMJ center mass will still put a grown man on his butt, and the 230 HST will make sure he never gets back up. So I carry a .45, until and unless they come out with the .46
Y'all be careful out there.