This is an unused premium barrel made by Criterion Barrels, exclusively for American Defense MFG. It's web source can be found at:
Chambered for .223 Wylde. 1:8 twist. 12.5". Carbine Length gas port. 1/2x28 threading. Nitrided. The works.
I bought it thinking I could mount an A2 sight base onto it, but the Hybrid Contour only allows for a gas block. The block size it'll accept is .750; it's been dimpled for easy installation. Again, this is an unnused barrel. Brand spanking new from the factory. All I did was take it out of the package and realize it wasn't going to work for my XM177 project. I've had it too long to be returned back to ADM, so I'm trying to sell it at a discount in an attempt to recoup some of the loss. Feel free to send questions my way.
If purchased, I'll send an invoice through Paypal, under the shop name of, Selling Stuff.