Here's how to judge the pragmatic case for gun control: if the pro-control lobby managed to have each of its favorite restrictions enacted, could we as individuals be more casual about our safety than we are today? The answer clearly is no. So what's the point of the restrictions beyond letting their advocates feel good about themselves?
A false sense of security is worse than no sense of security at all.
Mass shooters have obtained their guns legally, having had no disqualifiers in their records; used guns legally obtained by someone else; or obtained them despite existing laws. Therefore, the controls most commonly called for would not have prevented those massacres. In the latest massacre, the shooter had a disqualifier — a less-than-honorable discharge from the Air Force after a year in the brig for domestic abuse — but the Air Force failed to report that disqualifier to the FBI and so it never got into the database that was checked when the shooter bought guns from licensed dealers. New controls, such expanded background checks, would not have prevented the shooting because the Air Force was already required to report the shooter's conviction to the FBI. Even a ban on rifles with certain features, misleadingly called "assault weapons," would not have prevented the shooting because equally powerful rifles would have been available
Thus the victims of the latest shooter, like the victims of the previous mass shootings, would have been no safer under the sought-after gun-control regime than they were at the time they were murdered.
But this is not the end of the story. Even if those shooters had been unable to obtain their guns as they did, it does not follow that they would have been prevented from committing their monstrous offenses. How many times must it be pointed out that someone who is bent on murder is not likely to be deterred by legal restrictions on the purchase of guns? The gun-control advocates pretend that legal methods are the only way to obtain firearms, but we know that is not true. People have always been able to obtain guns through illegal channels. Gun-running — firearms smuggling and trafficking — is probably as old as the earliest gun restrictions. Guns can be stolen and sold. (There are 300 million of them.) Guns can be made in garages. Guns will eventually be made routinely on 3D printers. Supply responds to demand. Black markets thrive whenever products are prohibited.
But the black market — by definition — is already illegal. So what are gun-controllers to do, make the black market doubly illegal? I don't think that's a solution.