When you're animating, the best way to get things to look good is to assume a complicated animation will take you the whole day to get anywhere. Setting your standards really high is the only way to really start getting close to the beautiful animations people make.
So, some actual advice.
When you're doing a "reaction" to something, you don't want to do just rotational reaction, but movement as well. You may need to exaggerate it to show up for the camera, but it will make things more natural. Another thing is that when we "recover" from something, we tend to do so in like an arc. You'll notice this if you get like a broomstick and just play out your animations on it, you'll see how we "recover" from stuff. We aren't perfect.
With hand movement, try to involve less rotational stuff and more actual movement, as we're more comfortable with the strength of our arm than the strength of our wrist, if you get what I mean.
And finally, the best way to learn is to see other people's animations. Like go look at M249 reloads, or actual M249 reloads from real people, that helps too.
But, don't take this advice as your animations being shit. For a first full set, they aren't garbage at all. Just keep at it!