In a fit of sappy sacrasm, he asked, "How do you regulate a black market?"
Here's my comment:
What's your opinion? Please leave a comment.You really want to know how to regulate a black market? You turn off the tap. You require all guns bought by anyone anywhere to require a background check first. Then you license gun owners and register guns. Then you require gun owners to store their guns safely at home.
Those measures would stop the gun flow. Over about ten years you'd see dramatic improvement, not in regulating the black market and you sarcastically said, but in controlling the source.
And what is that source, it's you Sebastian and all your friends. It's the gun manufacturers and the FFL guys and all you civilian gun owners who let your guns so easily slip into that black market. Take responsibility for your part in keeping things the way they are, or actually making them worse.