Video Game Production Techniques - Creating an Animated Asset

Following the animation of my character, I was tasked with creating a basic animated asset, for this, I chose to use my firearm shown in the character animation set.
For this I would need to set up a basic skeletal rig for the pistol, to do this I created a root bone, and applied this to the combined Grip, Recoil spring and Disassembly lever, as these three pieces were to stay still and not move on their own.
Therefore the pieces which had bones applied were the Slider, the Barrel, the Trigger, and Magazine release button and the Magazine itself, the setup can be seen below:

I began moving and keyframing parts in order to get a rough firing motion, using vvideo footage, images and animated gifs as research and resource to help my animation flow.

I added both a general firing animation and a final round in the magazine animation, in which the slider stays back, slowing the slider release to come into play holding it back in place.
The magazine is then ejected and replaced, allowing the slider release to be pushed downward, releasing the magazine ready for firing again.

I may yet tweak this animation following peer review, dependent on feedback provided.

My current animation can be seen below:

I feel this has been largely a success and am happy with where my animation stands, but will gain feedback to get a further opinion on whether or not I need to add extra detail to the animation, or refine the details and movements perhaps, before the animation can be transported into Unreal Engine.