This will work to your advantage. Keep the discussion general, to the topic of gun control. Don't let yourself get sidetracked to one of the individual points for very long. The Constitution may be brought up, but I would advise against the firearms advocate from introducing it. We all know that the right to keep and bear arms is an individual right.
Gun control is an infringement.
By saying this, you are attacking all the various forms of gun control, not just one. The contention is short as a soundbite, and can be verified with everyday sources. It is aggressive and defiant, and puts our antagonists on the defensive, which is where they should be. I started out my discussion with the above contention. Later on in the discussion which ensued, he told of how he was afraid to be in New York City because of proliferation of firearms and the rampant crime rate that affects the city.