I’d just hard copy the rotation from the camera to the head bone, not the other way around. And to avoid slight shakiness from imperfect IK I would probably use the IK target bone for the camera location. Now getting the gun to align perfectly with the camera requires either really good IK or you do roughly adjust the upper body and then just yank the arms into the correct place relative to the camera. (I have no idea what Wolfenstein does since I haven’t played any of the Wolfenstein games)