I was in a gun store the other day and noted that they had short barreled uppers and rifle (stocked) lowers for sale and in inventory. This dealer is NOT a "class 3" or title 2 licensee, so what is the difference in the law between a retailer and an individual? Shops like this with similar inventory exist all over the country.
Without getting caught up on the terminology, the question in the thread is still clear.
What you are asking is parts together result in illegal possession even when not assembled.
The answer is complicated.
The ATF has had the courts rule against them, but they have chosen to ignore precedent before and say a court ruling against them means something different than it did, and thier interpretation is still the only way. Since they enforce the rules, that ends up being what happens.
The Thompson case is one of the more blatant examples in numerous ways.
The general consensus from ATF opinions is that if you have parts that can be assembled illegaly, they are still not illegal possession of an NFA item if they can be assembled in legal configurations with firearms you currently have.
So if you have a short barreled AR upper, and a AR lower with a stock, it is only illegal possession of a SBR if you cannot use them on other firearms. So if you also have an AR pistol and a long barreled AR upper, then all components can be assembled into legal configurations.
Where it gets complicated is the ATF has chosen to declare that having extra parts can be illegal.
Say you have 3 AR rifles, 1 AR pistol, and 5 AR stocks, perhaps because you bought some aftermarket stocks for your AR rifles, but still have the stock ones. Many people have an extra stock for a firearm, or extra components in general especially for a highly modular firearm like the AR.
Yet the ATF can declare that since you have 5 stocks, and only 3 rifles, that you have 2 more stocks than needed and in combination with the AR pistol you own that means you are in illegal possession of a SBR.
Likewise you may have multiple pistol barrels. You could even have complete conversion parts for some firearms to use all different calibers on legal platforms, all legal. But if you happen to have extra barrels for say your AR pistol, and you also own an AR rifle, then the ATF can declare you have a SBR because one of those extra barrels could be attached to the AR rifle.
Many people who own AR type firearms do end up with multiple stocks, barrels, and other components. Which is normally not a problem. Happen to own an AR pistol too though? It suddenly is a problem.
There is numerous similar firearm combinations where a rifle and pistol platform share components.
AK pistols, maybe even the Ruger 10/22 and Charger pistol.
To name just some common examples.
The ATF may consider some extra parts okay, or they may not. So they suddenly have a lot of discretion to declare you in violation of the law, and they have done so in the same circumstances before (and they will likely be nice and polite right up until the filing of charges).
Further if you were to sell one of your firearms, but retain some of the extra components for it, you could suddenly be violating the law. Own an AR pistol and a single AR rifle and then sell the rifle? If you had an extra stock, or vertical fore grip for the rifle, but sold the rifle, you no longer have a legal reason to have those components. You are suddenly in illegal possession of a SBR. I have seen stocks and grips better for different situations, so there is certainly reasons to have many. Some are more sturdy, but another one may fold away, one may have a built in light...maybe you want all of them for different situations?
Perhaps you purchased an aftermarket one, but saved the stock one in case you don't like your new purchase?
Perhaps after selling your AR rifle you plan to buy a new one eventualy, so don't want to get rid of your parts to spend hundreds aquiring them all over again (if they are all even still sold)?
Illegal possession of a SBR.
It would actually become "constructive possession" of an illegal SBR if you had a friend or family member hang on to the extra parts so you would not be in violation until you did buy that new AR rifle. Because you are still technically in constructive possession, intending to exercise control over those parts even though you are having someone else store them.
Constructive possession is just a legal term for possession when you are not really in possession. It has nothing to do with constructing or building.
What you have referred to as constructive possession in your question is merely considered illegal possession in legal terminology. Having a disassembled machinegun is still possession of a machinegun. Having a machinegun stored at your friends house is constructive possession of said machinegun.
