On August 13, 2000, about 1200 mountain daylight time, a Stinson 108-3, N573C, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, collapsed the right main landing gear during the takeoff ground roll at Campbell airstrip, Thompson Lake, Montana. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was substantially damaged and the private pilot and his passenger were not injured. The pilot reported that when he initially landed the airplane at the airstrip, it touched down hard. The pilot then taxied the airplane off the airstrip without further incident. The pilot stated that when he went to takeoff, during the takeoff ground roll, the right main landing gear collapsed. The right wing and right side elevator contacted the surface. Further inspection of the gear leg indicated that the failure occurred at a weld point. The pilot indicated on the NTSB Pilot/Operator Aircraft Accident Report Form 6120.1/2, that the part had accumulated approximately 1,569 hours.