My friend just bought this rifle because he just HAD to have a Colt and didn't want to spend more than $900 (got it for $815).  Anyway, the lower says .223.  I haven't SEEN it, but he claims the barrel says 5.56 NATO somewhere on it.  My question to you all is, is this thing chambered in .223 or 5.56?  Every place on the web I find a reference to it says it is .223.

I tried explaining to him that if it's .223 he should NOT shoot 5.56 though it but he says that he has shot plenty of 5.56 ammo though .223 chambers and had no problems.  I know he usually buys the Winny .223 from WalMart and THAT is safe to shoot though either chamber.

It's 5.56. Oddly enough the HBAR II has a 1/9ROT barrel rather than a traditional (for Colt) 1/7.

His barrel should be marked C MP 5.56 NATO 1/9 HBAR.

Good to know.  I thought the 1/9 was odd for a Colt also but he usually only shoots 55 gr anyway so it shouldn't be an issue.  I never though to check if it was chrome lined or not.

Never can understand why they bother to put .223 or 5.56 on the lower when they can be switched so easily between uppers.

Good question. I've seen mixed reports so I don't know either.


Doesn't make much sense to me either. All three of my Colts say 223 on the lower, but 5.56 on the barrel [rolleyes]

There are so many battles between Colt and Bushmaster on here that I can't believe that you guys don't know the specs for both.

Colt does not chrome line any of their post ban rifles except for their new M4 carbine. and I'm pretty shure that all of them have chrome lind chambers.          

Like I said, I've seen mixed reports and don't know who to believe. One of my shooting buddies bought a new Colt 6601 HBAR at roughly the same time I bought my new 6400c M4 carbine. He *swears* that his barrel is chrome lined but according to the FAQ here it isn't.

I'll reserve judgement until I can take a look down the bore and see for myself.

I've also seen plenty of people state that Colt only has a one year warranty, but my M4 came with a lifetime service agreement.