Not exactly… get the hand bone location/rotation in the local space of the shotgun sight socket and use that to place the hand bone in the camera’s space. Remember that the key here is that sight socket space and camera space are the same.
No interpolation here, this is the position the hand bone must be keep for as long as you’re aiming down sights. You only interpolate (or should I say let Unreal blend) when you’re going in and out of that aiming state.