Ive never met a single rational person in favor of gun control who is also in favor of getting rid of the 2nd amendment. All reasonable people on the left or right who support gun control simply want to make it harder to get a gun. Yes you cant take away the black market but thats assuming the person has access to such a thing.

The "black market" tends to exist for career criminals. You cant just go to some magical place and buy illegal things. Even trying to do so is fare more likely to get you robbed than anything. Especially when it comes to guns. Drugs are a commodity and need repeat business to survive. Selling someone a "black market" gun doesnt count on you wishing to sell them more. Someone engaged in selling black market guns probably would rather just rob you with the gun thus acquiring your money and keeping the inventory.

Putting up road blocks for crazy people to get guns, or for guns that cause mass destruction far too easily are the only arguments i ever here from rational people in favor of gun control. Those who take issue with all guns are in the extreme minority much like those who think you should be allowed to have Nukes as a "right to bare arms" freedom are in the extreme minority.