Certainly a valid concern. Though, it's close. It will be hard for communities without ammo to protect themselves in the wild or from other communities who do have ammo. This makes functioning weapons and ammo very very valuable.
Discussion
will 9mm be the reserve currency ?
depends on the situation, but it's a contender for sure
When fiat collapses, there may be many currencies. Scarcity drives value. Hell, I worked in Angola for a while and some of the guys coming in found that USB drives were so uncommon, people wanted them to take home and exchange for things. He was bringing a sports bag full in every month and making a killing as bloody USB sticks had effectively become a form of currency