Northmn.....The "Green River Barrel Company" you mention was probably "Green River Rifle Works", in Roosevelt, Utah. They made barrels, complete guns, and kits. Their "Hawken" rifles were about as good as a factory repro gets. They also had a powder mill, which led to their demise. It blew up, killing several people. The powder they made was excellent, comparing well with Swiss powder. I still have a couple of pounds of it. I also have a GRRW Hawken in .58 caliber that has never been finished. It had been in a time warp in Alaska for about 30 years.