Do yourself a favor and get an Oregon Gazetteer(sp) Map, this will show BLM and F/S lands. On these, you shoot all you like, just make sure you use targets (paper, wood, steel) not cans or bottles and pick-up afterward.
There plenty of places in your area, but by using the Map and Google Earth, you can save a lot of gas by picking out the most promising spots beforehand.
"One of the ordinary modes, by which tyrants accomplish their purposes without resistance, is, by disarming the people, and making it an offense to keep arms."
-- Constitutional scholar and Supreme Court Justice Joseph Story, 1840