On August 27, 2000, at 0922 hours Pacific daylight time, a Cessna 180, N2443C, sustained substantial damage when it ground looped during the takeoff roll from the airport at Cameron Park, California. The private pilot/owner was operating the airplane on a personal flight under the provisions of 14 CFR Part 91. The pilot sustained minor injuries, and his passenger was uninjured. Visual meteorological conditions prevailed and no flight plan was filed. The pilot stated he pushed the seat handle down after moving his seat to the desired position; however, his seat slid backwards when takeoff power was applied. His airplane was equipped with a secondary friction lock, but the seat only stopped momentarily. As the seat slid further aft, he reduced power. The airplane started to drift left, but he could not reach the rudder pedals. The airplane departed the left side of the runway and completed about 270 degrees of turn. The right main gear collapsed resulting in damage to the gearbox.