There were at best estimate in 1994 about 1.5 million at the time. Since then if estimates based on percentage of production, sales and requested background check, then the numbers have risen dramatically to 3.5 to 3.75 million of the assault-style or as the gun industry calls them "modern sporting rifles" in the US. Estimates of total gun ownership in the US is around 350 million so that means assault rifle is about 1 percent of the weapons out there. What is more, most crimes, the vast majority, are committed using handguns.
So would an assault weapons ban do anything? I don't know. What I do know is that in the recent mass shootings the primary weapon was the assault-style weapon. These guns are designed for shooting a lot of bullets and at a lot of people. I still don't know why anyone would own one of these except for show. The idea that someone owns one of these to protect themselves from the government is laughable. The evil government that you elected who has more weapons than your AR-15 at its disposal than you could ever possibly afford and is hardly going to balk at your assault rifle. Those who believe this nonsense are living in a very paranoid, tin-foil hat, wack-a-doodle world.
There is also the argument that these weapons are protected by the 2nd amendment but the Supreme Court would seem to disagree. As I pointed out, the most conservative of the judges, Justice Scalia, has stated that limitations and registration on such weapons would not be protected. Former Chief Justice Warren Burger, another conservative Supreme Court Justice, stated in 1991, "[The Second Amendment] has been the subject of one of the greatest pieces of fraud, I repeat the word 'fraud,' on the American public by special interest groups that I have ever seen in my lifetime." So again the idea that a ban would somehow violate the second amendment will not stand the scrutiny.
The same goes for the argument that the ban was in place during the Columbine shootings and didn't prevent it. By that kind of logic, I would point out that Columbine has armed security guards and that didn't stop it from happening either. You cannot use one piece of logic in the debate and ignore the other. The problem is that we already know that no one solution will ever stop crazies. What is true is that since its lapse, such shootings have gone up, but that also does not mean one follows the other because gun violence is down. The issue is not so much, I think, the ban as it is controlling these weapons.
Banning to some degree may be, to be trite, closing the barn door after the horses are out. Still, we need to get control of how these weapons are sold and who has access to them. I am not sure that the ban would do much, on the other hand is that if it stops just one mass shooting, then it is worth it because all the arguments I've heard against it just don't stand up. So I remain torn.