I Don’t know what did you mean exactly but what you can do is, Go to your character Skeletal Mesh and on the hand add a socket(it will be the point where your gun will be at) and then at your character you can add your gun Static Mesh and in the Construct Script Attaching to the player Via Socket.
My weapon have a grip , i modified the animation and i made that i hold the weapon for the grip but when i play i continue keep hold the weapon in default way .