Had to contemplate a moment on how to rivet these gusset plates. You can squeeze some but others have to be bucked. You will notice that not all my rivets are installed in the same direction. Why? Well, from past experience I have found that if you buck a rivet shop head on the small flange side, the flange will separate from the bulkhead. So, for all the bucked rivets, I put the shop head on the larger surface bulkhead. This way the rivet gun is pushing against the smaller flange preventing a gap from forming.
I took pictures of both sides of all 4 gusset plates to document for the FAA that they are all installed properly.