It was likely a hand made gun. Like a 3d printed thing
Why?
That still leaves a substantial paper trail, the real gangsta move is always the OG move. Just buy one used from a "private seller" without even an ID let alone a background check.
Like, if you think building a p80 would be less risk, you have no idea how easy it is to buy a gun without a background check in America...
How do you find a person who sells guns illegally?
It's not illegal...
If I want to sell a gun. I can sell it to a person I see walking down the street without even asking what their name is. If you've ever walked by a gunshow parking lot, that's something that actually happens.
They could have just gotten out of 40 years of prison, unless I explicitly know they can't own a gun, I literally and legally can't break any laws by selling them one.
Which is why lots of "private seller" don't ask names.
I don’t think that’s as easy as you think
If you don't want to wait on a gun show, lots of online websites exist to facilitate private sales.
I'm not saying it should be like this, I'm saying this is currently American law.
And there are a metric shit ton of loopholes, that no one seems interested in closing.