M1A should be chrome lined. (IIRC.) I know that the M14 is, and the M1A's were originally constructed with (mostly) M14 parts; these days, it's anyone's guess where the parts are from.
About the combloc weapons: it's iffy. My memory of the pistols is failing me - too many years, too many beers, as they say. I know that the Mosin-Nagants are not chrome lined. I'm not sure if the original SKS's were and I'm not inclined to hit the books right now to find out. The AK's were - whether this was from the start or not is for others to answer, as I'm by no means well-read in the field - but Kalashnikov, by his writings and interviews, was concerned first and foremost with reliability and I'd expect that a chrome lining was one of his design criteria. (His firearm was also the first Russian rifle engineered from the ground up - and expected - to shoot frequently in a fully automatic mode. I'm specifically excluding pistol-caliber submachineguns and the SVT's from this statement; SMG's are apples to oranges and the SVT's, by all accounts, did not work well in a fully automatic mode.)
I oversimplified the issue and for that, I apologize. Many of the armies of the world, c. WWII, used long guns around .30 caliber. Most of them were bolt actions. Very, very few had the capability for select fire. The ones that did were primarily machineguns and featured either water jackets or very heavy (and not very portable) barrels; in these cases, an unjacketed barrel will work. (The ones that did not - like the BAR - had other provisions for extending barrel life. Browning specified a 20 round magazine for a reason.) It will wear out more quickly than what is expected but hey, they're replaceable. For shoulder-fired weapons with barrels that're difficult to replace it's a different story. When weapons started appearing that were expected to sustain very high rates of fire, chrome linings appeared. The caliber drop merely drove the issue home for those that hadn't already jumped on the wagon.
Again, IIRC, the Garands (amongst others) had chromed bores. It's been a while since I've hit the books and honestly, I haven't kept up on my reading in this area. I seem to recall the American weapons having chrome linings from very early on. If this is the case, they had plenty of experience in the area. (If I'm wrong here, then I'm simply talking out my @ss and should be duly reprimanded for such.)
In the civilian firearm market, things can become trickier. Sometimes for a given model, some pieces have chrome and some don't. I don't know if this was the case for the M1A and won't make a guess.
Just for the record, I'm a big fan of chrome lined barrels. No one but dedicated match shooters will notice a difference in accuracy; all shooters will notice a difference in durability and ease of maintenance. If you saw some of the things that we do to our bores, Munk, you'd cringe. They just keep on plugging along. Chrome lining (or something similar, ala Glock's Tennifer process) is one of my criteria for purchasing a firearm in most cases. I'm a believer.
Edit: those who know say that the best M1A's were the ones assembled with government parts.