PRM 073 - Columbia River Arms with Carl This week Carl comes on to talk about what Columbia River Arms/Black Hole Weaponry barrels and more! Carl designed his own minimally invasive rifling and has been making barrels for a long time! This is a follow up show to the one done about a year ago and before I had a chance to try their barrels out! so far its a hammer and I'm very happy with it! it is a great show where he lets us into the world of precision rifle barrel making and gives us a heads up for what they have coming down the pipe!