Setting Up FPS Animation Triggers

I am brand new to this and am teaching myself the ins and outs by making a basic fps. I want the player to be able to pick up and drop weapons at will, to do this I have the players hand model (a child actor attached to camera) switch out depending on what gun is picked up (this is because the weapon and hand meshes are combined to make animating easier). The problem comes when I want the hand mesh to play any animation (walk shoot run ect.) I tried casting to it but I cant seem to find a way the cast wont fail. Does anyone have a solution for this or can point towards a method that would work?