The pilot reported that he was landing his tailwheel airplane at his home airport at the conclusion of a cross-country trip. The approach and touchdown were normal. The tail came down “a little sooner than I expected” and the airplane briefly lifted off again a few inches. After the airplane touched down again, it began to ground loop, and departed the side of the runway about 1/3 of the way down from the approach end. The airplane continued through the grass and down a drop off, striking several large rocks before coming to a stop. The left main landing gear sheared off and structural damage to the lower fuselage and left wing resulted. The pilot stated that the accident was “pure pilot error” and there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.