I have no idea and even most armorers probably wouldn't since I doubt they keep a tally of every single bullet fired by an actor.
If I had to guess, I'd say Arnold Schwarzenegger. After using the Minigun in T2 and machine guns, shotguns, handguns, and so on in many of his films, it'd be pretty easy to guess he's the ultimate blank firerer.
Shame he's a dumbass politician now... :P
"Ahng! I will fuckin
g punch yoo!"
(sorry, you can't write a dumb accent)