When demand goes up 500 to 1000 per cent, the factories can ramp up production with some overtime, but hiring new workers, training them, and quality control is not cheap, nor overnight. It takes weeks, if not months, to get a new worker up to journeyman level, for the simplest of duties. Not to mention the raw materials need to be ordered, and that supplier has the same bottlenecks as the final factory does. If my need for raw brass is up tenfold, but I can't increase production beyond an additional 30 or 40 per cent with overtime, I'm not going to have the cash on hand to front ten times as much raw brass. I'm going to have to wait until I have paid orders in hand before I can buy the materials, or tap out my cash reserves, which inhibits payrolls, etc., etc. There's a long pipeline out there, about 6 months long, it starts with and order and ends with delivery.
They're not making 43 calibers at the same time; they'll run the Gov't needs, 9mm, .308, etc., year-round, the rest of it is once or twice a year runs of
.25-06 or whatever.
Now add in the important factor; all of these makers are also filling government contracts, for police and military needs. They come first, it's just the way it works. The civilian market gets the surplus and runs on spare time, in a way.