Its panic buying, the ammunition plants are not the ones that control supply, the distributors and the delay between the distributors and the factories and stores are the issues.
There could be 20 million rounds of ammunition to satisfy everyone who is in the buying craze right now in the supply line, the ammunition factories figured it would be a repeat of 1994 with Clinton but with the internet, ease of communicating cross country etc, they figured right and over made ammunition for the commercial market.
They finished this large amount of ammunition then they turned down the production. Remember other then firearms, which are bigger and bulky compared to ammunition (and even reloading equipment where the companies do not generally have the ability to make more then they already do per day), it does not take much spare space to make a large over run of ammunition, and its preferred because what they make today wont hit the market for 3-6 months due to the delays as I understand it.
Reloading supplies also suffered because production of loaded ammunition would have been the goal, therefor the reloading components wouldn't have been made, instead focusing on making more components for the loaded ammunition, and only now in the middle of the panic buying are we seeing the supply ruin dry while the factories are starting back up to supply their distributors the reloading items.
At least that is my take on this, give it time and the supply will be normal again and supplies will cost just about the same as they always have.
Dimitri