I initially tried making the bullet a physics body rather than a character body since it would have been easier to simulate air resistance. Ultimately I didn't have the time, patience, or understanding to do this, but would it have been better if I did? The only other way I can think of changing the movement is to change how the recoil 'upgrade' works, but I doubt that would make it feel better to play. Glad you thought it was interesting, thank you!