i think you're confusing the massive and well-funded military lobby (the people who make 40mm autocannon) with the mixed civilian/military/police small arms industry (who make your everyday .223 AR-15). it's much harder to make it in the latter as a small businessman due to massively onerous regulation.

edit: tired of this. i own lots of guns and have never killed anybody. i had this same argument with somebody else yesterday over financial KYC: we do not fight crime by stripping law-abiding Americans of their freedoms and subjecting them to increased state control.