Drilled the right skin to the skeleton. Adjusted the HS-607 rib with a long flexible rod prior to drilling. Removed and deburred the left skin, then dimpled it. I used the Avery C-frame tool for most holes, but I had to use the squeezer for the forward edges, and I used a pop-rivet dimple-die set for the forward four holes in the center. On first one, I used the wrong size nosepiece on the pop-rivet tool, and the nail got stuck. I had to take the tool apart to release it. D'oh! Undaunted, I deburred and started dimpling the left skeleton.BTW, the Avery C-frame riveting frame is a great tool!
(Yes, it was cold in the hangar that day!)