Yeah, I always assumed that Wonder Woman can take low level gunfire easily, and could probably take even a shotgun to the face. Even assault rifles would probably leave nothing more than a light mark. However anything higher would shred her.
I do remember a comic that shows Superman and Wonderman deflecting bullets. Superman ask why she is using her bracelets when she is pretty much invulnerable as he is.
Cue to the bullets going to her boobs and the shooters start getting amused and just keep shooting for fun. :)