Update 1/16/15:
Part of this order was the AAC Nitride Barrel Brownell's had on sale for $119.
When I received the barrel I noticed the inside of the barrel extension area is brownish red. I can't tell if the barrel extension was installed after the nitride finish. I clean out the funk, apply oil, and to me, it looks like the barrel and inner barrel extension are bare metal. The brownish red stuff is only rust, not grease. I figure with the price of the barrel, I'd try and clean out the rust and see what it looks like.
I wanted to mock up the upper, and went to loosely install the barrel, upper and PSA SPR hand guard. The barrel index pin is too long and sticks out too far so the barrel nut can't thread over it.
Due to the Christmas holidays I didn't run out and send the barrel back right away. I'm sorry but I didn't feel like waiting inline for hours just to send this back. I did return the barrel after the holiday. As of today I have not heard anything from Brownells, nor know if they received the package. Good thing I have the tracking number that shows it was returned.
Pics of the AAC barrel below. I posted about this in the AR build section also. Not about Brownells, but about the quality of AAC.
Index pin too long:
Inner Barrel extension pic. This was after I cleaned it out and degreased it.: