Finished riveting both HS spars. I riveted the 3 nose ribs in the right HS skin. It is easy to rivet the end nose ribs with the squeezer but very difficult to rivet the center nose rib. It requires reaching in and blindly placing and holding the bucking bar while using the rivet gun on the outside. I screwed up one rivet and while drilling it out, I accidently elongated the hole. I decided to dimple that hole for a -4 rivet and installed a -4 rivet which has a slightly larger manufacured head, covering the hole completely. Phew... thought I would need to order a new skin. I will place a dab of sealant on the backside of that rivet just in case.