I have a post ban MT6601 20' bbl marked CMP5.56 NATO 1/7 HBAR  Wanted to know if this bbl is chrome lined.

No, the barrel is not chrome lined.

Would that mean the chamber is not?

Also anyone know why Colt is not using chrome lined bbls on MTs?

According to the chart [url=http://www.ar15.com/forums/announcement.html?b=3&f=118&id=172]here[/url] your HBAR is chamber chromed.

The Colt MT6400c M4 carbine has a chrome lined chamber and barrel.

Does anyone know for sure that brand new 6601 HBARs don't have a chrome barrel and chamber? The reason I ask is that a few months ago when researching my MT6400c I called Colt and they specifically said that new 6601s have [b]both[/b]. I specifically asked about the 6601 and the 6400c.

I'm wondering if things may have changed since Troy's chart was created. Colt also has a lifetime service agreement, and that conflicts with the one year warranty that is indicated on the chart.

Is it a bad thing to have a bbl w/out chrome lining?

Not particularly. Just not quite as good as having one fully chromed. Colt started out making totally unchromed M16s, and only went to Chrome lining, first the chamber, then the whole barrel, when the conditions in the Viet Nam jungles started eating up the chambers so that the guys were getting malfunctions from rusty and pitted chamber walls. They went to lining the whole barrels when they decided that unrusted rifling was as important as unrusted chambers[:D]

Unless you're planning on fighting a jungle war in Southeast Asia anytime soon, the unplated bore shouldn't cause you any problems.  I have two M16, Viet Nam era, lookalike pieces.  One is a dup of the first Air Force M16, the other an M16A1 duplicate. The M16 version has a barrel like yours; plated chamber, unplated bore.  The A1 version has a later, fully plated barrel. They both shoot exactly the same size groups w/mil spec ammo, and I expect both of them to outlast me[:D]

Thanks much for the info.

Where is Troy when we need him ?  [:)]

Still seems that the more $$ Colt bbl would be chrome lined??

?

[b]LOOK[/b] at the muzzle.
If you see a ring of metal that is different color than the thick part of the barrel, that is the [b]CHROME LINING[/b]. If not then it doesn't.

I'll check it in the am, thanks all!