What are the rules on the private sale of ammunition? If I owned 100,000 rounds and wanted to unload, say 10,000 rounds, does the government step in and prevent me from liquidating some of my private property?
It certainly doesn't look that way.
https://www.atf.gov/firearms/qa/license-required-engage-business-selling-small-arms-ammunition
Of course that's just Federal. State/local laws might be worth checking on.