Not sure about Glenwood springs. If you drive back through the canyon you can shoot at Gypsum Gun Club. Get off the Gypsum exit and go left, across the highway. take your first left, and that will take you to the range. You can walk in if the gate is closed. There is an opening in the fence for walk-ins. I think you need to pay $5 per person and fill out a waiver at the rifle bay. Just don't shoot up the target stands or shoot rifle at the steel, except on the rifle range.