I think there are a few things going on. This is all speculation of an industry outsider.
In the wake of a legislative push that probably surpassed the one we saw in '94, you get a few things...
1) Cabin in the woods hoarders. Buying it and putting it away. I think this dies off quickly after the news cycle.
2) Serious recreational shooters - people like me, who might have bought a box of 500 bullets are now buying 2000 so that we don't get caught short again and miss a day at the range due to ammo shortages. That alone is a 300% in demand from these customers. Think about what that means for supply.
3) Supply is very capital intensive (expensive machines/real estate). Committing to higher supply is a decision that isn't made lightly and has financial repercussions for years. It may take a while for folks to think it through before committing. And even if they do, it's not an overnight process.
4) Similarly, the ammo business is (I would guess, since all manufacturing businesses are like this) as profitable as it is efficient - nobody wants unused manufacturing capacity. That's burning money. So hesitancy to expand is understandable. If you expand for a temporary spike, all the profit you gain could be lost when your machines sit idle after the spike passes.
5) New shooters. Gun sales are up. Bullet sales will also go up. This is happening much faster than it has in past years based on NICS data.
6) Increased interest in reloading. The internet is to blame for this. More and better information is attracting more people to get into the science of accuracy. That means us.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Also probably a few who (strangely) think that if they reload the government cant stop them from having ammo.
All in all, it's not entirely surprising. The good news is that it's somewhat attributable to solid industry growth, which means more shooters, which means more people engaged in protecting our rights. I just wish they'd catch up already.