These started life as Wilson Premium Air Gauged barrel blanks. 1 in 9 twist. 5.56 Match chamber. Target Crown. Threaded. 6 flutes in front and behind gas block location. Finish: Manganese Phosphate. These are not M4 feed ramps, but there are Enlarged/improved feed ramps. we also made our own barrel extensions for these. Gas Port: carbine length. Gas port size: .062", we did not do it overly large as quite a few asked for something a little less gassed so after market piston systems can be more easily added with better function. I have not shot one of the 11.5" barrels yet, so there is a chance it might need to be opened just a hair for DI operation (probably fine with a suppressor on it. you can always take material away (opening it up), but you can not put material back.
There are 3 lengths available: 16", 14.5" 11.5" all NFA rules apply to the sub 16" barrels. Price is $215 shipped. add 3% for paypal, money orders also work just fine