You will get the bronze and silver bullet trophies during your two playthroughs of the game but there is a good chance you will not get this golden trophy. You may end up a few hundred shots short. So after you have finished the game on both rookie and veteran load up “Hawk Eyes – The Escort” and fire your unlimited machine gun until you unlock this trophy. The gun will overheat but just wait a few seconds then start spraying again. Repeat until you get the trophy.
You can check the progress of this trophy at any time from your profile stats in the main menu.