What barrels are on the latest production of the M16A2?

From the Bushmaster FAQ:
[red]Q. Are heavy barrels better than standard barrels? What is the difference between the heavy and the standard?

A. Yes, heavy barrels are better - they take much more heat without distorting. Currently, only heavy barrels are being made. The so called standard weight GI barrels of the early Viet Nam era are no longer the mil. spec. and have not been in production for several years. The difference is thickness (diameter) - the "standard" was machined down to a surprisingly thin profile primarily to save weight. It was quickly discovered that those barrels warped from the heat of full auto use, or they got bent beyond use by soldiers falling on them during training.[/red]

Are the standard weight barrels they are referring to these barrels?
http://www.bushmaster.com/shopping/barrel-assemblies/abbl20a2.htm

Has the military ever used HBAR barrels?

My HBAR barrel seems unnecessarily heavy. If Bushmaster would sell rifles standard with fluted or regular profile barrels, I would have not chosen the HBAR.
[:/] [?]

I think for an extra $50.00 they will flute your HBAR barrel??

For the civilian market, BM has no fear of barrel warpage from FULL AUTO fire or abuse in training.

I was thinking of turning down a HBAR barrel to lighten it up.  I have a 16" HBAR to give it a try.

OSA