On my optics mod for SH3 you will find the PDF Don mentioned, with a long explanation about it all. Yes the slide rules were used, some attached to the scope, some for standalone use without it by the IWO.
The truth is, top commanders (Germand and US) were normally able to gather the relevant data for a firing solution (AOB, speed, range) from guesstimation by naked eye through the scope. All those wheels and plotting (Wazzo style) did was back up and confirm what the commander estimated and refine the data. The TDC did the rest
