The test for initiating a Terry stop is that the officer must have a "reasonable suspicion based on clearly articulable facts that a crime has been committed, is being committed, or is about to be committed." The key factor is "clearly articulable facts." The Terry decision specifically stated that a mere hunch is not sufficient.
The officer stated that he had familiarity with similar-appearing firearms that are fully automatic (not surprising, since the firearm in question was designed to look like its full-auto big brother). Normally in cases of bogus Terry stops I tend to argue that the officer at best had only a hunch, and did not have any clearly articulable facts to support his suspicion. For once, I'm going to reverse course and vote with the officer.
Fact: It looked like a firearm (and there would be no way to know otherwise without an examination)
Fact: It looked like a full-auto firearm (and there would be no way to know otherwise without an examination)
I think it was noteworthy that the idiot almost immediately stated he wasn't going to provide ID, but the officer never asked for ID. The officer (once he cut through the idiot's BS) went right to the point: Is this a full-auto firearm or a semi-auto firearm? Once he had ascertained that it was semi-auto, he handed it back and didn't pursue asking for ID.
Kudos to Officer Nork. Well played, Sir.