As to domestically manufactured ammo I have a theory on that too. When metal prices were so high, ammo manufacturers only bought enough to get by on. Now there is a lack of ammo from the lack of purchased materials. It will take time to build up inventory of supplies.
I know a lot of people blame the military on the shortage too--nah, ain't buying that. Those contracts are set and agreed on way ahead of time. The ammo manufacturers know what they need for that.
New shooters, ok, maybe some of the problem. I know people who have bought a gun, or guns. since BHO was elected. Hence the salesman of the year.
lastly, I believe the ammo manufacturers did not want to get caught with a lot of inventory in case something does get flushed down the Washington pipe.
Just my opinion.