Back riveted the rudder stiffeners to their respective skins. Assembled the R-1004 halves and rudder horn, and riveted this assembly to the right skin. Instead of following the assembly instructions I should have back riveted the R-1004B half to the rudder skin, then assembled the R-1004A half, rudder horn etc. onto that, because with the R-1004 halves already combined, the aft most rivet to the skin is a complete pain to buck.
Riveted the R-1003 rib halves to their respective skins, and then used pulled rivets for the first time on the project to mount the shear clips onto the stiffeners on the right skin, ready for assembly.