RANGERS AT WORK: Paul Ehrhardt (left) and fellow volunteer ranger Eric (last name withheld) repair a Forest Service cabin in Oregon's Willamette National Forest. Some object to rangers carrying weapons. ROBERT HARBISON - STAFF JUNCTION CITY, ORE. - The gray Jeep Cherokee with the large gold star on the door is just about ready to roll. Two men check the gear stowed in the back: tools, medical equipment, radios, GPS device, rappelling ropes, camera, gas mask, body armor, canisters of CS gas and pepper spray, thermos of coffee, and sandwiches. They're both wearing badges, and they both have semiautomatic...