On July 29, 2023, about 1205 mountain daylight time, a Cessna 177, N3357T, sustained substantial damage when it was involved in an accident near Gillette, Wyoming. The pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he and a passenger were on a multi-leg cross-country flight from Whitman Regional Airport (OSH), Oshkosh, Wisconsin, to Felts Airport, Spokane, Washington. Witnesses reported that the airplane had been fueled before takeoff from the Northeast Wyoming Regional Airport (GCC), Gillette, Wyoming. Witnesses observed the airplane depart from runway 16 and reported that the engine seemed to be at full power. The pilot reported that during takeoff at a gross weight of 2,500 lbs., the airplane did not climb as he expected. Shortly after the airplane crossed the departure end of the runway with rising terrain ahead, the pilot made a shallow 180° right turn and elected to land in an open field as a precaution. The airplane impacted a hay bale during the landing flare and the airplane subsequently nosed over. The airplane sustained substantial damage to both wings and the fuselage. The pilot stated that he had previously executed takeoffs with full fuel during the trip. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. Postaccident examination of the airplane confirmed flight control continuity from the cockpit to each control surface. Review of the airplane’s airworthiness revealed the engine was changed from a Lycoming O-320 to a Lycoming O-360. The airport's automated weather observation station reported that, about the time of the accident, the wind was from 180° at 16 knots, gusting 21 knots and a temperature of 80.6°F. The airport elevation was about 4,365 ft, mean sea level (msl). Runway 16 was 7,501 ft by 150 ft. The calculated pressure and density altitude was 4,035 and 6,607 ft, respectively. An owner’s manual (OM) for a similar make and model of the airplane with an engine comparable to the accident engine reported that the maximum gross weight is 2,500. The OM allowed for the flap settings to be at 0° to 10°. The calculated takeoff distance from a hard surface with flaps 15° at a maximum weight of 2,500 pounds, and travelling at an indicated airspeed of 65 knots, was about 678 ft for the ground roll and about 1,524 ft total to clear a 50-ft obstacle (assuming 2,700 rpm, a 20-knot headwind, an altitude of 5,000 ft msl, and a temperature of 80°F). The calculated maximum rate of climb at a maximum gross weight of 2,500 pounds, and travelling at an indicated airspeed of 89 knots, was about 470 feet per minute at an altitude of 5,000 ft msl and temperature of 80°F.