Good morning, hope all had as good a Christmas as I did.

I picked up a slightly used (150 rounds) Colt MT6700 for Christmas. Does this rifle have the chrome lined barrel and chamber? The barrel is marked C MP / 5.56/NATO 1-9.
I know the 1-9 is the twist rate and the 5.56 tells me that it's a military spec chamber and so I can use civ .223 or mil-spec such as xm193 / m855 etc.
To this point I've put 120 rounds through it getting it zeroed and seeing what kind of 3 shot groups I could get at 100yds. Best to this point is right at 1.5in. I am not a complete newb to the AR series of rifles having spent 12 years in the Army but I do realize that what we had (M-16A1 in Germany, M-16A2 when we deployed to the sandbox and then M4A1 when I was sent to Bragg as part of SOCOM) isn't quite the same as the civilian counterparts.
Thanks for the help guys!!!

The barrel is not chrome-lined but it doesn have a chromed chamber.  The "C" stands for "Colt".

Edited to add: Where are my manors?  I just noticed this was your first post so let me be the first to welcome you! [beer]  

I'm not into Colt model number trivia.  You can determine if the barrel is fully chrome lined by removing the flash supressor and looking at the muzzle end, the chrome finish in the bore should be fairly obvious.

If this is a HBAR barrel you'll notice it's much heavier than the M16A2.  Lighter profiles are available for a couple hundred bucks.  

[url=http://communities.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw]Inproved Battlesight Zero[/url] will work on this rifle.  Standardize on ammo and get a 1000 round case.  Winchester Q3131 or Q3131A highly recommended.

-- Chuck

Thanks M4....I've lurked around for a couple of months now but wanted to actually own one before coming in and asking a million questions. I will probably put 400 - 500 rounds a month through this thing....would it be in my best interest to spend for a chrome lined barrel on it? I'm not looking for match accuracy since I don't compete and have no intentions of doing so...I just want a good plinking rifle that can serve as a good SHTF backup to go along with my SKS.

Chuck....it doesn't have a suppressor or brake on it....it's a standard Match Target Competetion HBAR manufactured sometime between 1998 and now. It's basically an A3 configuration, detachable handle but no burst or FA obviously.

A chrome lined barrel will certainly be easier to clean and should out last a non-chrome lined barrel.  If you have the money then I would say to swap the barrel out for a chrome lined one.  If you want to keep it all Colt then look for a "blue label" one on the Equipment Exchange.  It will not have a bayo lug so all you have to do is replace the FS with a brake like a Wilson, Kurt or Cav Comp.

Actually I'd shoot the snot out of this barrel and hope that next September brings the "semiautomatic assault weapon" nonsense to a close.  Then you can fit a standard M16A2 barrel to this receiver.

-- Chuck

Welcome to the board!

Its a standard Colt competition rifle.  It will group better with match grade ammo.  I think you will find its too heavy SHTF type stuff.  Put in a KAC two stage trigger in it and shoot it.  The tube will last between 10 and 15K rounds depending on how hot you get it.  I would put the A1 furniture on it.  When budget permits get another Colt upper and put a DPMS superlight BBL in it.  Wrap it in some kind of a rail system with a light & laser for when the power is out.  Pop two pins and switch as needed.