BSA assembled bikes in batches usually to order but casting & forgings were done as a continious run till the moulds needed servicing
The parts got stored in stillages till needed for machining so could have in theory been sitting around for years .
If you look at any of the period movies or sets of factory stills, in the background are stillages full of partially finished parts.
While not as efficient as Just in Time used today, it was overall very cheap.
If the furnace held 5 tons then you made 5 tons of castings weather you needed them this week or not.
I am not sure but it is most likely the date would be the maching date, assembly date or inspection & passing date rather the casting date as they would have been casting for several weeks till there were enough castings for the tool setters to set up the mills & lathes to machine the cases.
When this was done they were all measured and stamped according to the gauges that fitted.
They are the funny litle letters, numbers or just weird stams you find all over the place usually in locations that are out of view on an assembled machine.
Weather the comp shop machined their own gearbox cases or not is unknown to me but I would doubt it.More likely they got a pallet of "A" gauge box cases then built up the various competition clusters into them.
Last edited by BSA_WM20; 03/25/21 10:04 am.