How to make tactical reloads and advanced gun animations

So right now I am trying to make a tactical reload and fire animation for my guns (taking out mags and switching chambers), something like this. How would I go about animating this so when I actually play the game I take out the mags and replace it with new ones, etc?
TLDR: How do I make gun animations that work in game withs several parts and both hands involved?
Thanks in advance.

viewmodel, and gun & hands rig