How to copy animations from arms to another set of arms

I'm not sure how I can perform this task. I have two sets of arms for a first person shooter, 1 set that is fully animated that shoots a gun, etc. Another set that is a beautiful PBR asset but not animated at all. How can I port the assets from one set of arms to another? Maybe even with the Animation Controller?
I tried duplicating the mesh of the original and duplicating those animations but I couldn't add them to the arms. Any help would be great.

 

This can be accomplished externally pretty quickly - skinning the PBR arms onto the animated bones. Max/Maya have a skin wrap modifier that can do this in about 5 minutes.
Internally - the transforms of each bone can be copied/pasted to other bones as long as they meet a couple points, same size/length/orientation/scale, name, and one other criteria I can't remember right away.
Otherwise - I believe some assets can assist with this task.

 

Thanks for the reply. Although I don't have 3-D Max or Maya. I'm not even that good with blender. For assets the only thing I do have is Umotion pro although I don't know if it will do anything like that.

 

Might look into blender - see if they have a comparable solution to the skin wrap modifier as Max/Maya does.
Seems like it does, though don't know how new user friendly it is.
https://blenderartists.org/t/skin-wrap-type-of-modifier-or-tool/598359