The demand increase has signs of being permanent or close to it. Based on NICS checks, in 2019, gun sales averaged 1.16 million a month. In March 2020, with Covid fears, there were 3.7 million record checks. After the George Floyd protests started, June and July saw 3.9 and 3.6 Million. I saw recently it seems to have settled in at about 2 million a month now. Vista Outdoors president Jason Vanderbrink said in one of his videos that another part of the increase was unexpectedly due to Foodies becoming hunters both to have an outdoor safe-distancing activity during Covid and to participate in the locally-sourced food movement. Apparently, their numbers turned around a multi-year decline in hunting, and he said he thinks they are now likely a permanent market addition, too, and they've made record amounts of hunting ammunition to keep them supported.
All those new guns need ammunition, and the ammo makers have added employees and shifts, and it took them a long time to be able to start keeping up. There's been a new primer maker added in Texas, but there's also been a new ammo maker added down there. So I think the shortage of primers has mainly been their diversion to ammo making in order to keep the plant shifts working and the new gun owners and users supplied. This simple market forces explanation seems likely to be the real issue, as adding the complexity of conspiracies on top of that and all the people who'd have to keep them secret while still paying inventory taxes on their stock makes it much more complicated. As Occam's Razor has it, more complicated explanations are least probable, particularly when they would have to be in addition to all the known market forces already eating up supply.
