50 years ago July 2, 1976 Perhaps the oldest participant in Pittsburg's massive bicentennial festivities will be the city's solid brass cannon, nearly as old as the nation, which will roll and roar again on July 5. After six months of ordinance duty, Frank Bresnick, head patternmaker at McNally-Pittsburg Manufacturing Inc., has pronounced the 170 year-old cannon ready to thunder a salute to America's 200th birthday.