If they're criminal people who plan ahead they realize that AR-15s have suddenly become a quick trip to jail.
They're only going to jail if they get caught. And it's really hard to get caught if your only witnesses are dead or too terrified to testify.
and then people start throwing death threats
Cite your proof. I want to see your proof that multiple people were making multiple threats and then I want to see the proof that those people were gun owners. Until then you've proven yourself to be a blowhard that knows nothing.
Criminals like Adam Lamza will steal from lawful citizens, therefore if you make it illegal to own AR-15s and high capacity ammo clips and do a mandatory buyback criminals will no longer be able to find AR-15s with high capacity clips.
How exactly is this mandatory buyback going to work? Cause I think if I were a criminal with a AR15 magazine and they announced a mandatory buyback, as soon as I got done laughing, I'd start figuring how my illegally owned and wholly unregistered stack of AR15 mags were going to help me out.
Although, the sheer price of such things would keep them off the street (how many people do you know can afford to buy a $200,000+ tank?).
Screw buying one. Make one.
The irony is that the people you claim are protecting their families are using their guns to make death threats against others.
Cite your proof. Cite the proof that: (a) there were multiple people making multiple death threats and (b) those allegedly doing the threatening actually own guns. I don't own a single firearm. I am pretty staunch in my support for the 2nd Amendment.