Jockey Gregg McCarron, who won 2,403 races in a 24-year career and is the brother of Hall of Fame jockey Chris McCarron, died Thursday at his home in Airy, Md., after suffering a heart attack. He was 77 years old.  A native of Dorchester, MA., Gregg rode in 20,595 races during a career that started at Suffolk Downs in Boston in 1969 and ended in Maryland in 1993. He was the leading apprentice rider at Rockingham Park in 1969, according to Chris McCarron.  Gregg rode mainly in New England, New York, and Maryland and he trained horses for a short while on the Maryland circuit after he quit riding.  :: Access the most trusted data and information in horse racing! DRF Past Performances and Picks are available now. Gregg McCarron rode multiple Grade I winners On the Sly (1977 Jockey Club Gold Cup), Bounding Basque (1983 Wood Memorial Stakes), and Broom Dance (1982 Alabama Stakes). In total, he won 29 graded stakes including the Cherry Hill Mile, the Secretariat Stakes, the Selima Stakes, the Ladies Handicap, and the Spinaway Stakes. Among the other horses he rode to victory were Mom’s Command, Tiffany Ice, Before Dawn, Vision, and Mademoiselle Forli.  After he retired, McCarron became a racing commentator for NBC Sports, covering the Breeders’ Cup for several years.  “Gregg led me to my career as a jockey and he was there for me every step of the way,” Chris said in a release. “He was my idol and I always tried to emulate everything he did. He mentored me in my formative years and I would not have had the career I did without him in my life.”  Gregg is survived by his wife Darlene, son Matt, grandson Trevor, eight siblings, and numerous nieces and nephews. Matt is a retired two-time champion steeplechase jockey.  No memorial service is planned at this time. :: Want to learn more about handicapping and wagering? Check out DRF's Handicapping 101 and Wagering 101 pages.