The second bulkhead did not need any shims but the third one did. I used a .040 shim for almost half the circumference of the bulkhead. This is the aft side so the shadow is not a gap its where the radius of the bulkhead meets the shim.
I need to final drill the skins to the longerons, debur, dimple and rivet the skin in place. I’ll leave it off for a while so I can easily get to the inside as a lot of equipment is remote mounted; transponder, second comm, elt, etc. For now I’m keeping the PC680 battery on the firewall. Look no pucker at the clecos.