Started riveting on the left top skins with the help of Genevieve. She was on the mushroom bucking bar on the shop head side and I was ont he double offset back riveting set on the shop head side. Riveted 2/3's of the field rivets, startiing at the center of the ribs and moving to the edges.
It was somewhat difficult to get a good shop head with this method ... they tend to fold over a bit if not exactly alinged. Also, I needed significantly higher pressre on the gun ... 40-45 psi, rather than my normal 30 for size 3 rivets. Had a few drill-outs when Geneveive didn't keep the pressure on sufficiently.
Hand riveted the aft spar with the gun and bar; the angle of the flange made the squeezer slide off.