If you are on public land and it's not big game season when you are out, you should be fine for rifle and pistol west of I-25 just out in the National Forest or on BLM land. If big game season, could always call ahead to the DOW office in the area and just ask/get permission so they don't hit you with a trumped up poaching charge.

Just do a google maps scouting trip and get some ideas. If 100 yards is all you need, plenty of places to do that without needing to be at a range proper.