[6] In August 1973, immediately before his Freshman year at North Carolina State, he won the 200-meter butterfly at the AAU National meet in Louisville, Kentucky, with a personal best 2:04.11, upsetting 1972 Olympian Robin Backhouse by .4 seconds.

Swimming for Coach Don Easterling, he captured a national championship in the 200 Butterfly in 1976 and was an ACC champion six times during his four years at NC State.

Gregg finished second to Mike Bruner, whose 1:59.23 broke the World Record of 1:59.63 of Germany's Roger Pyttel set a month earlier.

[12] Gregg took a silver in the 200-meter butterfly at the September 1973 World Aquatics Championships in Belgrade, Yugoslavia, with a time of 2:03.58, just .26 seconds behind American Olympian Robin Bakhaus, who he had upset in the event in the AAU Nationals a few weeks earlier.

[14] Still swimming competitively and not far off his Olympic time, Gregg placed first with a 2:00.84 at the AAU Long Course National Championships in the Woodlands, Texas, outside Houston on August 5, 1978.

After retiring from competitive swimming and completing his education, he marketed Gatorade for the Quaker Oats Company in Brussels, Belgium for around six years.

[10] He also served on the International Swimmng Hall of Fame board of directors and provided early guidance to the Swim Across America organization.