exposed barrel threads

Not sure about cross posting from forums, but as this is a possible safety issue...

CMP Discussion Forum - 3 digit carbine

The guy claims it's a 3 digit SN, '45 barrel, and has visible barrel threads. Says it functions fine. I posted that he needs to not shoot it and get it inspected. Any learned people here have an opinion?

I'd be willing to bet that he has a carbine built using a commercial receiver and GI parts. Said there was no mfr identification by the serial number. Hopefully he'll post a pic or two. My .02 worth......