That is why you are wise to have a good rifle or two, a shotgun and a trustworthy pistol you can comfortably carry.
Add to this a modest supply of ammo for each firearm and you have this department covered.
Hoarding is misguided at this time though may be appropriate for trading purposes toward the end of this year.
But there is the problem, your definition of a modest amount of ammo is just that, your definition.
My definition is quite a bit different.