That's a tough one. If the firearm in question only operates in semi-auto then I'd say yes it's legal. I noticed when I did my 5 minutes of research on them, it seemed that most came with a select fire feature. If the firearm in question has this feature then he will probably need to get a tax stamp. There are others on this forum who know way more about this subject than I do and can help you further. Remember, this is only what I think I know. I am not your or anyone elses lawyer and as such cannot be held responsible for the actions that you take after reading this information.