Jack Pierce of the Leon Braves hits his 46th and 47th home runs, breaking Hector Espino’s 22-year-old Mexican League record. He will finish with 54, aided by the lively Commando ball the league has been using.

On July 17, 1986 Jack Pierce of the Leon Braves hits his 46th and 47th home runs, breaking Hector Espino’s 22-year-old Mexican League record. He will finish with 54, aided by the lively Commando ball the league has been using.

Source
Baseball Reference July 17