Just stop repeating things that are false. First among them is the bizarre notion that anyone at all can walk into a store and buy a gun that can "spray bullets" by "holding down the trigger". That's right out of the elitist liberal playbook that assumes most Americans are totally ignorant and so can be jerked around by lies if they're repeated often enough. It's the equivalent of quoting Glen Beck as an authority.
The facts of federal law have been posted: it's impossible to buy that kind of weapon in any store at all in the U.S., not just for felons, but for anyone. To own such a weapon, you have to qualify for the required federal license, and then persuade one of the limited number of people who own such a weapon to sell it to you, from a selection where the cheapest of such weapons now goes for $12k. It would actually be easier, if you're in the southwest anyway, to buy one from a Mexican drug cartel (it would probably have come in through Guatemala, with a good chance of having been made in Europe or China). That's part of and/or a result of the National Firearms Act, which someone already linked (easy enough to find on
Wikipedia if nowhere else). It's the same law that makes "sawed-off" shotguns illegal and made pipe bombs essentially illegal because they fall into a category of device the Act requires to be registered with the government.
Since these facts have been posted, what am I to assume but your deliberately ignoring them?