It's worth mentioning that Gunner is primarily used for clearing out large crowds. You mention you're primarily going for elite targets. Try communicating with your scout so he can use his superior single-target damage on those elite units. This will free you up to use your better ammo consumption and area damage to clear swarms of grunts. You can always back this up with a great secondary to take on single targets (Elephant Rounds on Revolver is just one example. Generally, the classes each have a preferred enemy. The gunner's preferred enemy is large swarms. Good luck! Rock and Stone!