The National Archives Modern Military Records in College Park, MD would have copies of the General Orders awarding the Bronze Star, if it was awarded during wartime (more about that later).However, you'll need the exact unit and General Order number in order to get copies. If you have his discharge papers it would be listed there.Alternatively, you can make a trip there and wade through the unit GO's yourself, or pay a professional researcher crazy money to wade through them for oyu
Even if you do find the citation, you probably won't get much information.GO Bronze Star citations generally run no longer than two or three typed lines, with little or no information other than name, rank, unit, and date.
There were three "types" of Bronze Star awards during WW2.A soldier could receive a BS for HEROIC action, that is, an award for a specific action on a specific date.There were also MERITORIOUS awards, basically awards for actins over a longer period of time.
In 1947 the govt authorized the Bronze Star retroactively to any soldier who had recieved the Combat Infantry Badge or Combat Medic Badge (basically front line infantry soldiers).