Motor6d rig animating weird?

So im using motor6d on a arm rig to make fps arms, and the way i rigged it is all the gun parts to 1 piece of the gun and connected that with the right hand, but it behaves strangely. My arms are rotating when trying to rotate the piece I motor6d’d to the right hand, any help?

this is a common motor6d error, it is more than likely caused do to the pivot of the gun/arm, try to update the pivot to the center of the arm and try animating it then.