Sorry, Kaitlyn, I sorta zoned out when you said "automatic weapon". Those have been effectively banned for private possession in the USA since 1935. However, I see your point, I think, regarding semi-automatic weapons with way more firepower than necessary for hunting.
First, let me point out that the Second Amendment is certainly NOT about hunting. Hunting can be completely banned on any federal property and it would not violate the Second Amendment.
Second,as a Constitutional right, we have to be more than a little careful about how we regulate who is entitled to actually exercise that right and how we decide. The general rule on such fundamental rights is called "strict scrutiny", i.e., "statutes that burden constitutionally protected rights survive only to the extent that they are no more restrictive than necessary to achieve compelling state interests." Lutz v. City of York, PA, 899 F.2d 255 (1990) at 269. Creating new statutes to survive strict scrutiny in the courts is not as simple as saying, "this is really, really bad so we shouldn't allow it any more". Would that it were. You cannot simply say, "this gun is bad" or "nobody needs this gun since only gangsters use them", since it begs the question, "why deprive any competent, law-abiding citizen of the right to self-defense?"
Third, each State has its own constitution and laws. The Federal government cannot actually ORDER the States to follow federal laws, although federal courts can certainly overturn state laws that violate federal rights. Maybe you're not aware that there are actually states where there is no gun law at all. You need no license, permit, background check, waiting period or even ID to lawfully purchase a gun. Fact is, this used to be true in MOST states; you went into the hardware store, plunked down $100 and walked out with a new gun, like buying a hammer (which can also be used to kill).
So, not only do you need some sort of federally sanctioned framework, each and every state would need to enact its own gun laws, drafted to survive strict scrutiny in federal courts, and then enforce them.
That ain't gonna happen.
Fourth, our "messed-up laws", as you put it, also allow over a 70 million people to have guns that can be used to STOP crimes, far exceeding any possible ability of all the police in the whole country to stop such crimes. You have to weigh the risk that passing some law (such as the total ban on concealed weapons in Aurora, Colorado and gun-free school zones) won't have the unintended consequence of increasing crime against those made more vulnerable. You could be turning "good citizens" into "bad gun owners" who won't risk using a gun if you're being raped or robbed in their back yard, since they could have it confiscated when the police show up.
Finally, as suggested by others, if you have some psycho who is willing to murder his own mother and steal her firearms (or go into a gun shop and murder the clerk, or ambush a state trooper and take his guns), what POSSIBLE law would prevent that? Maybe Mr Lanza's mom was a nice, sane, conscientious person and would be perfectly acceptable under your new plan and could, in fact, legally own a semi-automatic rifle and pistols and store them inside an approved safe when not actually using them. Now your local gangster kicks down the door, threatens to kill her if she doesn't open the safe (similar in shops and police situation), steals the guns and murders anyone he wants. Show me the law that will prevent that. Laws are for punishment and deterrence, not for prevention. What law will prevent someone ignorant of the law from punching you in the nose? None.
As they taught us in Executive Protection school, if someone is willing to die trying to kill you, there is very little you can to do stop them. They pick the means and the time and place; you have to be constantly vigilant and take reasonable steps to be prepared at all times.
Having armed (and properly trained and supervised) guards at schools and other soft targets would seem a good place to start, along with requiring locked doors on classrooms. I wouldn't be surprised if we see schools being sued for "negligent security" if any more kids are killed, based upon the proof that such carnage is now "foreseeable" and that "reasonable steps" can and should have been taken to prevent or stop it.
Executive protection, police academy, attorney