In the Jenkinson book at least three home runs are listed as going further than 502 feet.
Left Field- 510 ft, Jimmie Foxx 08/16/1940
Center Field- 515 ft, Babe Ruth 06/22/1927
Right Field- 540 ft, Babe Ruth 05/16/1926
I was at Fenway last month for a 2 hour tour, and the tour guide said that Jim Rice and other guys have it further, but the balls left the park, and therefore, Ted Williams' home run is the "longest recorded home run at Fenway".
I don't know, maybe they just don't want someone other than Ted Williams having the longest home run. :idunno:
Maybe Granite knows what the deal is.