D'oh! Yes, I see the four in the slot now. I'll detach my camera and have a look at the end wall I'm just a curious cat...
I just made Duke. Going to stop grinding rank for a while as it's becoming a bit repetitive - mind you, it was quite lucrative: nearly every other mission run had at least a 10mCR delivery reward for 180 palladium. Add to that the other stuff that could fill my hold and all the poll and courier stuff with time bonuses, I think I made 150mCR since I started the grind
Well with that sort of funding just build yourself an armoured and shielded brick then fly into a station without docking permission and look for where the shots come from.
Alternatively you could do the grind another 10-100 times for the funds for a Fleet Carrier. Well at least for the deposit for one.