I've read that recently CMMG was making LW or a1 profile 20", 1/7, chrome lined barrels. I have to assume that they stopped making them because demand dropped. It seems to me like many things retro, or at least lightweight are making a big comeback though. How likely is it that we'll see new barrels of this type being made by a major manufacturer again in the future?
I have to imagine that if a manufacturer wanted to save cost then plenty of folks would be fine going with a nitrated barrel instead of chrome lined (although nobody seems to be able to show any long-term durability comparison test results, nitrating seems to be an OK alternative at least), while cold hammer forging ends up being cheaper in the end and is known to produce tough barrels. I'm guessing some very decent barrels could be made at an acceptable cost to the manufacturer.
Of course personally I drool at the thought of a Noveske-style m249 spec'd 20" a1 profile barrel.... while they are now making a LW 14.5" barrel it would be against their philosophy to make a 20" of this type (since they maintain that increased barrel length is only good for long distance shooting, so any 20" barrel should naturally be SS/match, not machine-gun rated...)
Also, let me know if this would be better posted in a different section...
CMMG hasn't made an A1 profiled barrel for about 3 years now. Unfortunately, they were ahead of their time with those. They had them available before the retro craze started gaining popularity. That and they were priced a bit high for that time so it took them awhile to sell the ones they had made up, so they're probably a bit reluctant to tie up a bunch of money with inventory they feel might just sit on the shelves again.
I think your best bet would be to see if Green Mountain could do something for you. They have an A1 profile barrel coming out, and they can do 1/7, 1/8 and 1/12 twist barrels so they may do something custom for you if you're willing to pay enough $$$.