Of course. If the new gun laws are enacted, gun crime will disappear the very next day.
No, of course the new laws would "prevent Newtown" or any other recent mass shooting. These things take years, even decades of serious enforcement for these laws to become effective, to root out the caches of guns already owned, and to change the perception of guns already ingrained into the culture.
As one poster pointed out, these efforts are mostly symbolic, a way of saying "we're sick of this and we're going to do something about it." Because of our strong gun-loving culture, the first baby steps must be taken toward big, unambiguous... um... targets,
i.e. things that make headlines and stay on the news cycle for more than a day.
But anybody who gives even the most perfunctory glance at gun statistics will see that military-style weapons are not the major gun problem in US society. Not even close. Not even rifles of any kind. Not knives, clubs or polonium 209. It's handguns. If we are ever serious about reducing gun crime in the US, we must address ways to keep handguns out of the grasp of criminals, drunks and mentally unstable people. Nobody addresses this problem because the solutions are so difficult and the ownership of pistols is so widespread, but if you're looking for the weapon of choice in most crimes, you need look no further than your own, snub nose.
Maybe this legislation is a way of "getting the foot in the door", and
it is so obvious that nobody needs military-style weopons and large ammo clips that even conservative messiah Ronald Reagan said it many years ago. But such laws, while slightly better than nothing, are still a weak and nearly cosmetic attempt to address a problem that is much much bigger, and completely unaffected by any such laws.