Ling made his Olympic debut in 2004 at the age of 21, and finished 25th, improving by four places in 2012.
But he took silver at last year's World Championships in Grenada, and an excellent display in Rio gave him victory 13-9 over David Kostelecky.
Rio 2016
Fourth time lucky for Germany's Engleder in 50m rifle
11/08/2016 AT 16:36
Rio 2016
Steven Scott takes bronze for GB in double trap, dances with gun to celebrate
10/08/2016 AT 19:03
Rio 2016
Anna Korakaki takes gold in shooting for Greece to bag second medal
09/08/2016 AT 20:43