I think that a few hundred rounds is sufficient per weapon. At some point you will run out of other things, and either have to venture out in groups or defend what you have. Otherwise stockpiling ammo is futile, as why would you need to stockpile it under normal conditions, if you are just talking target shooting or hunting.
That's whaen you really would need to evaluate your situation, not for a shortage of range ammo, Obviouslly no one will be shooting at paper if there is an ammo shortage. No need to advertise what you have for no good reason. Most times when everyone is doing one thing, it's the few who make money, from contrarian thinking, that are doing the opposite.
IE:One guy says I have 5000 round per gun, I ask, how much body armor do you have, usually answer is none. Does anyone feel that they can resist a barrage of thousands of rounds of incoming ammo just because they bought a lot?