You're off your rocker, stop making an absolute fool of yourself by talking about shit you don't understand.  Individual sales of firearms in United States is perfectly legal, as long as all trades adhere to local, state, and interstate laws.  For example, I can sell a firearm in my state as long as the transaction is facilitated by licensed dealer (third party.)  Interstate sales are also legal as long as the firearms are shipped to a licensed dealer for transfer within the legal confines of the purchaser's local laws.

If you don't believe me, go tell the ATF that all the registered users of gunbroker.com are violating your interpretation of American firearm laws.