At 07:20 central time, a Cessna 182 struck trees during takeoff from a private grass airstrip near Victoria. The pilot was not injured. The pilot said the left seat slid back about the time the airplane rotated. Subsequently, the airplane veered off the airstrip and struck trees near the departure end of the runway. The inspector reported that the seat track pin holes were within the manufacturers limits. The pilot said he did not have the safety lock installed on the seat track.