You'd want something like this instead since aiming angle has its own function.
Code:
self.<Emitter>.RotAngle = self.<Actor>:GetAimAngle(true)
or if you always want the guns angle just get the gun's angle itself.
If you get the actor's Rotational Angle then your getting the angle his torso is. I believe GetAimAngle gets the angle of the head or where your cursor is aiming in respect of the selected actor.