I’m glad I’m not in the ammo manufacturing business right now. You actually have a very weird situation where demand is through the roof but actual consumption is down. Most everyone I know is shooting a lot less now due the the skyrocketing cost of replacement ammo and covid. Most are panic buying ammo “just in case” and just putting it on the shelf. This creates a real problem for the manufactures, since ammo has a very long shelf life (I’ve been know to shoot 40+ year old Greek surplus .30-06 in my M1s). So there is this huge overhang of unexpended ammo out there. The manufactures have to decide if the actual consumption of ammo will go up after all the panic buying or if the demand will just plummet as people consume their on hand stocks. The real question for them is if the 7+ million new gun owners are going to actually shoot their guns, or be the kind that buy a gun, a box or two of ammo, and then just let it sit in some desk drawer.
I’m pretty sure even some of us regular shooters have stockpiled more ammo then we would ever need (at least in some calibers, I know I have way more 7mm Rem Mag then I’ll probably ever shoot). And of the stuff we do use regularly (22lr, 9mm, .45, 5.56x45, etc) if things settle down we might not need to buy anything for a year or two since we’re so overstocked in those calibers.
This is why I just don’t see the manufacturers adding significant capacity in the near future. It’s still too soon to say if the actual consumption of ammunition has gone up significantly from its historical norms.