I have a Daniel defense outer barrel, 13.5” long, 14mm- threaded end. Threads are perfect. I wire wheeled the finish off the barrel after drilling it to lighten the unit. Steel barrel. Extremely solid, and a must have for any build. Set screw to lock inner barrel in place. Trades welcome. Interested in vsr10 bolt handles (AA, maple leaf, or Laylax). 20.00 shipped