Having zero knowledge of S&W but being involved with other complex assembly product manufacturing. My guess is reality works this way...
The Boom Revolver company makes guns in .22, .32, .38, .41, .44 and .46 calibers. It has one MIM machine which makes frames in 3 sizes using 3 molds and 6 cylinders in 6 calibers using 6 molds.
It cold forges 30 different barrels (6 calibers in 5 lenths) on one forge using 30 different mandrels.
So this 'cycle' the boss decides to make 100 .32s and 1000 .22s and 50 .46s based on sales. He has just those two machines to make parts for those models. So no medium frames are made until later, how much later, well if demand for small and or large frame revolvers goes up, it might be a while.
But unless the molds need to be retooled, eventually everything gets manufactured, albeit in smaller limited runs. For smaller concerns deciding when to make the switch can be difficult because every change decreases production and incurs fixed labor costs which must be spread over a production run be it 10 or 10,000 units.