On February 1, 1996, approximately 1615 Pacific standard time, a Christen Industries, Inc., A-1, N2866B, operated by the U.S. Department of Agriculture on an exclusive use lease, was substantially damaged during a collision with terrain while maneuvering. The certificated commercial pilot sustained minor injuries and the passenger was uninjured. The accident occurred on the frozen, snow covered surface of Goose Lake, approximately five miles southeast of the Lakeview Airport, Lakeview, Oregon. The flight, which was to be operated for the purposes of animal control, was public in nature. Visual meteorological conditions prevailed and no flight plan had been filed. The aircraft had originated from Lakeview approximately 1400 hours and was on a local flight. In an interview, the pilot reported that while executing a low pass in the vicinity of a coyote the gunner's weapon jammed. The pilot, concerned as to the direction in which the weapon was aimed (towards a fuel tank), shifted his attention to the gun barrel to move it away from critical aircraft areas. During this event the aircraft's main gear touched down on the snow covered lake surface. Tracks from the wheels indicated a ground roll of approximately 30 feet before the aircraft nosed over. There were no references on the surface of the lake, e.g., fence posts, trees, brush, rocks to provide the pilot with depth perception cues. An overcast existed which filtered the late afternoon sunlight reducing surface shadow effects, and the sun angle was low at the time of the accident.