First they have to be legal in the state you live in. I don't know what state that is, so I cant tell you if they are legal where you are. They are legal in the majority of the U.S. Basically, if you can walk into a store that sells firearms and purchase one legally, you are qualified to purchase a full auto legally. (NO felony convictions)
There are two ways to obtain full autos. The first is an individual process.
You must have the following:
2 Form 4s.
2 photographs of yourself attached to the Form 4s.
The CLEO must sign the form 4s. (usually the County Sheriff, but there are others that can qualify).
2 Fingerprintcards.
1 Citizenship form.
$200.00 check or money order for the tax stamp.
All of these things are sent together in one packet.
One other thing you must have is patience. The transfers are taking 60-90 days right now. My last one took 90 days exactly. The BATFE is a federal agency and they do not get in a hurry.
The forms are available either online at
www.atf.gov Or, the BATFE website gives you a toll-free number to call and you can actually speak to a human.
If you find an individual in the same state as you who has a full auto that they want to sell, no dealer is required. All you have to do is fill out the paperwork and send it in to BATFE and wait for the return of the Form 4 and it's yours.
If it is in another state, it must be transferred from a dealer in that state to a dealer in your state and then to you through the dealer in your state. This will result in the payment of two transfer taxes and whatever fees the dealers charge for the transfer and the shipping.
The other method is to form a trust. I know very little about this method cause I've never done it. The advantages of a trust is that you do not have to have fingerprint cards, pictures or CLEO signatures.
You also asked,
Where did they find the people to sell them these weapons? How does an M60 machine gun get put out to the public?
Some are found here:
www.subguns.com
There are others, just use Google.
There are thousands out there, but they can be expensive. Thanks to a change in the law May 19, 1986, there is no further new manufacture of fully automatic weapons available to the public. Anything created after this date is considered "Post 86" manufactured and can only be sold to Law Enforcement agencies (not individual officers) or to the Military.