Very good job !! I couldn't understand the controls at first but I was so excited with the music, the idea and the art that I persisted and tried every key so allow me to add instructions here :
When you are the little helper use arrow keys or wasd and space bar to move around. Left click with the mouse to destroy the stuck bullet. Put a bullet in the barrel and then use E and A or D to move the wheel to engage the bullet. E again to shoot on the bang button.
It was so fun when I got it. The game is so charming and the level design great. Hope you can polish it with a game over/retry menu, tutorial, and other levels with other guns in the future.