I'm personally a fan of silhouetting, but I'm also not an accomplished animator, so take what you will from that. ^^
What you have right now is not bad; it's fairly fluid. However, I think some snappiness would be nice. Cut a frame from the draw, and instead use a blur/streak to really emphasize the quick draw. More importantly, though, I think his leg movements could be exaggerated, to match the movement of the upper body more. Right now the upper body movements are fairly big, especially for a pistol draw, and the animation might benefit from a more pronounced backstep. Step that trailing foot back further, really exaggerate it like the upper body; that alone should give the entire pose more sass.