The Combat Naval Gunfire Support File (CONGA), 3/1966 - 1/1973 contains a record for every naval gun fire mission during that period of the Vietnam War.  Each record contains the date, time, target coordinates, rounds expended, etc.

Thanks to shipmate Bob Chase,  who scrubbed the raw .csv file into a much more readable .xls spreadsheet and plotted USS Newport News CA-148 targets on MGRS charts from the period.