Steve Lundquist set an American record in the 100-meter breaststroke and Tracy Caulkins and Mike Bruner each won a third event last night as the U.S. National Swimming Championships concluded in the wake of the U.S. Olympic Committee's decision not to send a team to the Moscow Olympics.

Lundquist used a tremendous start to open a half-body-length lead over John Hencken and Jeff Freeman and gradually stretched the margin to finish in 1:03.08, breaking Hencken's mark of 1:03.11 set at the Montreal Olympics in 1976.

Caulkins was ahead of the world record pace at the halfway point of the 100-meter breaststroke, turning at 33.45, but faded coming home, touching in 1:11.34. The world record is 1:10.31 by Julia Bogdanova of the Soviet Union. Caulkins also has won the 100-meter individual medley and the 200-meter breaststroke.

Bruner, of Mesa, Ariz., Aquatics, added the 1,500-meter freestyle crown to his earlier wins in the 200-meter butterfly and the 400-meter freestyle. The Stanford graduate was ahead of Brian Goodell's world record pace for 800 meters but slowed down the second half of the race and finished in 15:19.76.

Susan O'Brien, 14, of Curl Swim Club in Bethesda, Md., improved her morning swim in the backstroke of 1:05.56 to finish 12th in 1:05.44.

Sam Jones finished 14th in the 100-meter breaststroke in 1:06.6. Jones, 21, of Starlit Aquatic Club in Fairfax, Va. qualified for the consolation finals with a morning swim of 1:06.09.