Anyone know?  Thanks.

It depends on when it was made and what barrel profile it has.  Around the mid 90s-ish, Colt quit chrome lining most of the HBAR barrel bores, but I believe they still chrome lined the chamber.

Quoted: It depends on when it was made and what barrel profile it has.  Around the mid 90s-ish, Colt quit chrome lining most of the HBAR barrel bores, but I believe they still chrome lined the chamber.

It is a 20" HBAR 'Pre-ban' since the serial# <ST038100 (and Below - Pre-Ban) according to the tacked list.  So it would have been manufactured before 1994.  So from what you're saying, it should have a chrome-lined chamber and *possibly* also a chrome-lined barrel.  Thank you.  

Great.  Thanks for the replies!

Troy,
I don't believe any of the Colt 1/9 twist 20" HBARs were ever chrome lined.  Colt intended these barrels for target use.  I've owned eight or ten of these barrels, of various vintages, and none of them had chrome bores or chambers.

The 1/7 twist HBARs, at least the four preban versions I own, are indeed fully chrome lined.

[edited for clarity]

Troy,
  Sorry, it was not my intenton to call your expertise into question, I was only trying to relate my own experience.

I've owned two or three 6700s produced in the early '90s, prior to the ban.  They were, I believe, the first production flattop rifles, and are pretty rare.  I still have the barrels from these rifles, they're 1/9 twist HBARs.  I've also bought several others as replacement parts from various vendors over the years.  I can see no hint of chrome at the muzzle, in the bore, or in the chamber in any of these barrels.  There is also no "O" (or is it a "C"?) stamp at the chamber end of these barrels, like my Colt known-chromelined barrels.  I've owned scores of barrels, and it's generally been easy to tell which are chromelined and which aren't.

Having said that, I would like nothing more than to find out these barrels are, in fact, chromelined, because that's what I always wanted.

Respectfully,
George

My rifle has "1:7" stamped so from what you guys are saying it definitely is chrome-lined.  Thanks again.  I don't know what people did for AR-15 information before this site.  I'm just happy it's here now.

I have a preban 1:9 A2 upper sold as a .223 "conversion kit" (R6900DC) for 7.62 guns that is chrome lined.  Also has a recessed crown which I had never seen before.  Never fired it.