I strongly believe their barrels are nitrided. I know they aren't chrome lined for sure. I have been looking at them and seriously considering getting one and using it as my patrol rifle.
ETA: The barrel is nitrided but it appears the barrel extension isn't. The real happy thing about the rifle I got was that every mag I tried on it drops freely loaded and unloaded. I tried 3 different 30 rd PMAGs, 1 20 rd PMAG, and the Troy Battlemag. Looks like Troy fixed that issue.