So, feedback on the idle_pistol animation:
Works fine here.
In Blender, just make sure the the Auto-Rig Pro finger bones are properly positionned.
In UE, make sure you switch to the arms and its hierarchy (hands, fingers) to Skeleton. To do this, click the All Bones Active Sockets in the bottom area, check Show Retargetting Options. The click the arm_stretch bone, right click, Recursively Set Translation Regargetting to Skeleton.
Then, you can rotate the arms and apply a rotation offset if they’re not exactly where they’re supposed to be. Just click the Key button in the top area and apply for each bone you edit. Then save it.
In the example below i’ve only rotated the arms to center the hands. The fingers are ok, but if you need more precision you can apply a rotation offset too.
