Riveted the ribs, reinforcement plates and nut plates to the rudder spar after priming all the parts yesterday. Awkward rivets again inside the spar flanges. Rivets that I hit with the assistance of an extra pair of hands came out much better. The squeezer tended to pull the AN470-4s at a bit of an angle no matter how I tried to line up the yoke. Priming the inside of the skins next.