This barrel is pretty unique and started life as a 16" SOF chromelined barrel.

I had ADCO:

Cut it to 13" overall - from end of extension to end of crown. It is 12" from index pin to crown
Precision thread it for a suppressor mount
Drill gas port for more gas flow in the SBR configuration
Install VLTOR block with a single pin vs. set screws

This barrel ran about 95-98% for me over it's life, however I can not in good conscience sell it as a "perfect" barrel.

However, it will make a great barrel for someone wanting to fiddle with an SBR setup using an adjustable gas block or gas tube -- or simply wants to try and get it tuned up to run perfectly. Or might have aspirations of installing a piston retrofit kit. I do not have the time or inclination to screw around at the range.

Here was my write up: http://www.ar15.com/forums/topic.html?b=3&f=62&t=405745

$270 Shipped & Insured to the Lower 48

New ArmaLite 16" barrels run $350, Noveske SS barrels run $533. VLTOR blocks are $45+. This has a little extra work that you won't find on a factory barrel, and will cost you plenty tp get done.