Is it illegal to buy select fire trigger groups

[santacruzstefan]

I was under the impression that the parts themselves were legal. When I did my USC to UMP conversion, the UMP lower came with what I think was the parts necessary for FA. But it wouldn't fit on the USC upper. So the only way it would be illegal is if the cuts were made to the upper that would enable it to fit, and thus create full auto capability. So the way I understood it was, parts = ok, cut receiver = not ok, parts plus cut receiver = bend over. But I might be wrong...

edit: hmm... maybe not, after reading m03's post above.

[Arisaka]

^^ This causes problems for an HK (33, G3, etc.) build, until it's clipped and pinned, do you possess a MG?