IMHO, 1000 rounds for each gun you own.
In addition, a minimum of 2500 rounds for your SHTF guns. I keep a large stock of 9MM, 5.56X45 and 7.62X51.
An unopened case of 5000 .22LR is a good idea. It's always a good trade item as well as a practical item.
History fails to record a single precedent in which nations subject to moral decay have not passed into political and economic decline. There has been either a spiritual awakening to overcome the moral lapse, or a progressive deterioration leading to ultimate national disaster.
If you think a strong military is expensive, think about what a weak one would cost