The feet.
The feet seemed to be the only real thing wrong with it. They didn't move at all. You animated the body walking nicely but the feet moving would be much better. That's really it. Also one other thing would be to learn about kick back among different guns. For smaller guns like pistols, it would have a lot of hand movement, yet little to no body movement, and bigger guns like shot guns and rifles would have the type of kick back you had for the pistols.
So yeah.