Colt stopped chrome-lining the bores of their "civilian-profile" barrels (meaning: virtually any HBAR, and a few others) in '97, though they did continue to chrome-line the chamber.
Colt's military-profile barrels, such as 20" A2 and their M4 barrels (both the military 14.5" and the civilian/LEO 16" versions), are fully chrome-lined, as are any barrels that they may occasionally have left over from a contract run. For example, a few years ago, both Colt and Bushmaster made a bunch of replacement 20" A1-profile, chrome-lined, 1:7 twist barrels for the Israelis, and the extras were made available for civilian sales.
And, remember: Colt is the king of the exception, so you must always verify the specific parts you are buying to ensure you're getting what you think you're getting. Assume nothing.
-Troy