It is impossible to find every animation of our need on Mixamo of course. Thus, it is better to gain the knowledge of building animations by using Animation Rigging. In the Zombie Shooter game, I am going to create a Reload animation for the gun.
Create a new animation for the Gun and name it “Reload”. Drag and drop the new animation into the Animator of the Gun that helds the Gun Fire. Create a “Reload” trigger and attach it as a Condition for Transition to Reload.
On the Animation Window, click on Add Property and select position and Rotation of the game object so that it will save the initial position and rotation values.
Clicking on the Record button, we first create the bringing the hands up behaviour for clip change.
Then, we need to create the mag fall out and stick back in animations. Of course, the top of the gun also needs to give the sense that we are actually out of ammo.
The rest is simple Animation Recording. Not perfect, but does the job.