Cool animation! It does lots of things well, I think you have a good eye for animation. One thing I think might help you though, is the way you time each frame. Right now, many frames have different timings. This might seem good at first, but it really makes things way more complicated and difficult. With a regular frame timing, each frame represents a certain amount of time, and more importantly each unit of space represents a certain amount of movement between frames. For instance, if you have a single pixel moving one pixel every frame, a regular frame timing would give you regular movement. If the frames all had different timings, making that pixel move at a steady pace would be very difficult. With animation,
everything involves the change in position between frames. So with an irregular frame timing, you need to account for both the amount of movement and the amount of time represented by that frame. Very very tricky.
I can see you are trying to make quick things happen quickly by reducing the frame time. But there are better ways to represent the speed of an action. Remember that the
distance an object moves between frames corresponds to it's speed. For the gun recoil, it is meant to move quickly up and then slow down as she gets control of it. The motion blur you use for the gun, is actually a product of film. In film, each frame represents some unit of time (same as in animation). If the shutter speed is too slow, all movement occurring within that frame time will be captured (making a blur). That's why a motion blur makes things look quick, it represents to the eye a lot of motion in a short amount of time.
In the edit, I did a few very simple things. I made the frame timings regular. Then, I combined the muzzle flash frame (too quick to be represented by its own frame) with the first recoil frame. Finally, I increased the amount of recoil experienced and the response to it. The edit is still flawed. It seems to "catch" a bit before the recoil. This is because the muzzle flash frame has a small amount of change in position from the last frame. The frame after moves a lot more. Anyway, hope it helps a little bit.
Keep up the good work, I like what I'm seeing overall.