Criminals who were stopped or arrested for other crimes and found to have contraband weapons would have said weapons seized from their vehicle or home and not returned, the same way most illegal weapons are confiscated today. Thus, the supply of guns would shrink over time.
But then law-abiding gun owners would still get to keep all their guns, correct?
Well if they continued to possess an illegal firearm, then they would by definition not be “law-abiding.” My point is that the idea that banning some new category of weapon would result in the feds going door to door to everyone’s houses in Waco-style sieges is silly, as is the idea that gun control isn’t worth pursuing because it won’t result in the elimination of all guns overnight.
It wouln't work and would lead to a new War on Drugs.
An important difference being that you cannot brew a gun in your bathtub or grow bullets in your dorm room closet.