Actually, it wouldn't, for the very good reason that criminals won't obey this law any more than they obey any others. Also it would clearly violate the 2nd Amendment (liberals don't care). Lastly, it isn't just criminals who would ignore such a law. This isn't England, where the populace meekly surrender their guns just because the government says so. The citizens of the U.S. never will.
Let's get one thing straight. Gun control isn't about reducing crime. It's about making America safe for tyranny.
This is the same argument you get from them about bloggers vs. TV network news- the bloggers don't have the benfit of "experts" (that is, editors) to tell them what they can and cannot say. (They use the same argument to prop up an educational system that is manifestly failing millions of children). It is a mindset which is just about impossible to change.
For public safety all
people must wear MITTENS.
So people can't pull the trigger
on those evil assult weapons.