Finally a sensible counter-argument! Thanks for that!
I still disagree with your general premise, but I do see where you're coming from. As we all like to say around here, IANAL. As a simple layman with a very limited understanding of the law, I can't claim to be an expert on what the intricacies are when determining what qualifies as RAS or not. In this case, the observation was that the officer thinks the firearm is a restricted firearm. I concede the act of carrying in and of itself is not a crime - so long as the person carrying is not prohibited from doing so because of a permission slip. And that's the difference here between this and what I would call "normal" open carry (for lack of a better way of naming it).
The legality of carrying a fully automatic firearm is predicated on the idea that you have permission to do so (much like carrying concealed), whereas you don't need that same permission to openly carry a non-restricted firearm. Because the firearm in question appears to be a restricted firearm, the officer investigates. He does in fact think a crime may be being committed until it becomes clear one is not, at which point the encounter and detainment ends.
Carrying Pepsi isn't illegal, so once again, that analogy doesn't quite work. But carrying an open intoxicant is illegal in many places. What if I poured apple juice into a emptied whiskey bottle and was walking down the street drinking it? Would the fact that it appeared I was consuming an open intoxicant be RAS enough to be stopped and detained while the officer determined if I was committing a crime or not?
Since you responded to me, I'll respond back even though many others already have. The fact that you disagree with the premise does not make your argument valid. Your opinion on the matter is not settled law. This isn't an attempt to insult it's just a simple fact. That applies to my opinion as well. Opinions are not settled law.
The carrying of a "restricted" firearm is not illegal. Therefore there is no suspicion that the carrier was doing anything illegal. The point is that the LEO had to have some other information to identify that this particular person was not allowed to carry this particular firearm. Case in point, if the officer knows the carrier personally. And if he knows that the carrier does not have NFA license to own a fully automatic firearm. And if the officer sees the carrier with a fully automatic firearm. Then he has RAS to assume that there is crime being committed. OR if a friend called the police and told them his buddy is illegally carrying a fully automatic firearm and here's what he looks like. LEO drives over and sees a person roughly fitting the description of the guy. THEN he has RAS. But a MWAG call is not RAS to assume that there is, has been, or will be a crime. Therefore there is no justification of search, seizure, or detainment.
As to the issue of this sentence:
"The legality of carrying a fully automatic firearm is predicated on the idea that you have permission to do so (much like carrying concealed), whereas you don't need that same permission to openly carry a non-restricted firearm."
Simply put that is not true. You DO have to have permission to openly carry a "non-restricted" firearm in that you have to be legally able to purchase a firearm in the first place. Legally carrying a firearm openly is predicated on the foundation that you are legally allowed to purchase that firearm which leads to the ability to openly carry. Therefore, you fall into the trap of the simple act of carrying a firearm would allow RAS for search and seizure for any person. But as we all know, that has been struck down by the courts.
For this sentence:
"He does in fact think a crime may be being committed until it becomes clear one is not, at which point the encounter and detainment ends."
The assumption in this sentence is guilty until proven innocent and that stance is unacceptable in court. You cannot assume guilt until you are allayed. In fact it is quite the opposite.
The analogy of the "Pepsi" stands because carrying a fully automatic firearm is not illegal. The action of carry the firearm is not breaking the law. The position of owning a fully automatic firearm while not licensed to do so is the violation of law. Therefore the RAS would have to be directed at the owners legal capacity to own an NFA firearm. However, your analogy of the alcohol actually does break apart. You see the action of carrying an open liquor container IS illegal in most public places. The owning of the liquor is not. Therefore it would be more along the lines of the LEO stopping a person on the street who is exhibiting no signs of intoxication for carrying an open coffee thermos. Then the LEO says "from MY experience I can tell that thermos has alcohol in it." Essentially you are being stopped for no reason. Then the cop tastes the coffee and says, "Based on my training I am able to ascertain that this is not alcohol and is actually just coffee." You are showing no signs of intoxication at all and there is no RAS that you have committed a crime in carrying a thermos. Unless someone called the police and informed them that a man just poured alcohol into a thermos, etc.
The point being, that in order for a LEO to have RAS the suspicion must be linked to an actual crime. The act of carrying a NFA firearm is not a crime. It is the act of owning an NFA firearm without proper license that is the crime.
A line must be drawn somewhere. Else, we lose our rights completely.