Re: Chrome lined, light-weight profile .308 AR barrels
I've got a Fulton (Actually Kreiger Criterion line) 18" chrome-lined light weight profile barrel on a DPMS/Fultonstein build I made this year. Most of my bolt action precision shooting has been done on an FN SPR with "precision chrome" lined barrel. Some quality manufacturers seem to have figured out how to consistently apply chrome lining to a slightly over-bored barrel.
I like .308 AR blasters. I like short light weight barrels on blasters, especially .308s that are already heavy and long to begin with. I like chrome lining on blasters. They seem to extract better when dirty, and I am more comfortable with less maintenance on a chrome lined barrel than on a non-chrome lined barrel. Also, blasters get higher round counts between cleaning and just in general, which makes a more wear-resistant chrome-lined barrel a better option.
Armalites are a little different - Modified M14 mags as apposed to SR25 style mags, angled rear receiver profile instead of round, and I have heard, but cannot confirm that the Bolt/BCG and barrel threads are different.