Faustling:

>>They're buying them on a black market where they can get full auto.

As someone pointed out above, the difference between semi- and full-automatic is a $10 kit.

So why don't you just ban the $10 kit? Oh, that's right, it's already banned, with a 10-year federal felony for violators. So where are they getting these kits? And these kits would work just as well on guns whose stocks didn't fold and which didn't have bayonette mounts of flash suppressors, etc.

Besides, whose idea was it to let Mexican criminals cross the border at will?