I am not sure of gun laws, but suppose you bought an automatic gun in the 70s? Can you still keep it or do you have to give it up?
When you bought it does not matter. If it is registered in your name in the nfa registry and is legal in your state then you can own it. Even if you bought it legally in 1933 (one year prior to the 1934 NFA) if you still possess it without it being registered you commiting a felony. Answer the door. Thats the BATFE. Hide your dog.
Who cares if it's legal!? You will need it for Basso and Traderjorge's militia to overthrow Obama and his gun control activists! The activists will be unarmed. It will be shooting deer in the wild.
Automatic weapons which are registered under the NFA are legal to own, as are deactivated war trophies. If it wasn't registered in 1967 (at the time of the last general amnisty) or at the point after when it was made, it is illegal to own. If it is legal, you can't just sell it to the guy down the street. There is a process through the ATF that requires waiting a long time and purchasing a $200 stamp. If you need more information, let me know. If you have specifics, that might help. The one upside is that if you purchased it legally in the 1970's, it is probably worth more than 10x what was paid for it. This is because no new guns were registered after 1986. So supply & demand shoots the price up. Again, if it is legal and you give some specifics I could give you a rough price.
It is also illegal to own if it is not in your name you no longer have the paperwork (the NFA registry is a trainwreck, they have lost tons of documents) you live in a state in which it is banned. The awesome part is there are thousands of NFA weapons registered to dead people.
Based on the the threads he has started, my fear wouldn't be of him but rather getting in some kind of sketchy situation. I had more than enough legal trouble as a stupid teenager/young adult, which is exactly what he appears to be.