At 1700 eastern time, a Cessna 310F landed with the nose gear partially extended at Rockingham County/Shiloh Airport. The pilot and passenger reported minor injuries. The pilot said it was the airplanes first flight since its annual inspection. When the pilot tried to raise the gear, he heard a pop. When he arrived at the destination airport the gear would not extend. The pilot opted to land in the wet grass. The airplane touched down on the main landing gear, ballooned back into the air and collided with the grass in a nose down attitude.