You can’t buy “automatic weaponry” in the United States. It is SEMI-automatic — you have to pull the trigger for each shot.
Well, you CAN legally buy full auto in the US. But it’s gonna cost you a bundle of cash to do so.
Automatic weapons are tightly regulated, but you can buy one if you have new-car amounts of money and pass the anal exam, and have the patience to wait for big brother’s approval of your Constitutional rights.