From the ATF:

ATF Link



I think we can all agree that the last bullet point does not apply to platforms like the FN PS90 - since it's absolutely assembled and produced only as a rifle.

But what about the first? At what point does having a receiver and a short barrel qualify as making an SBR? Is there any case law to support when you've actually crossed the line to having a bunch of parts in close proximity - to a bunch of parts in close proximity that they serve no useful purpose other than to make a short barrel rifle?

If you had a stripped lower and a 10" AR15 barrel, you could argue it has a purpose to make a pistol. But what if you have a rifle where a pistol variant doesn't exist? Is a stripped receiver and a barrel (even unassembled) enough to qualify as "making" an SBR in accordance with 5845 (a) (3)?

ETA: I don't think any of us want to "be the guy who finds out", so this is primarily a hypothetical discussion. The safest course will always be to buy the barrel after you've gotten Form 1 approval for your SBR.

Decades of Case Law. Simple answer is make sure everything can be legally assembled. A few pistol assembles (no stock), makes sure things are not rifles. It is hard to give a blanket answer, but to your specific question about 10" upper and stripped lower, that is not an SBR since the lower has no stock.

There was a case, and actual conviction, for constructive intent where a person had a stocked AR lower and a short barreled upper.  I remember one important point in the case is that he had no other lower, nor any 16” uppers, so the only combination for a functioning gun with the components on hand was an SBR.  I think one thing with the PS90 is that both the barrel and receiver are unique components, so if you have a unbarreled p90 receiver, and the only barrel you have is a less than 16” barrel, that might be considered constructive intent.  Also, you can’t really claim it’s for a PS90 pistol since those don’t exist.

My take on it is this.  If you have a short barrel or short barrel upper, make sure that you have something on hand that it can legally be used on, either a pistol, or a legal SBR.

Is this a continuation of the PS90 thread?

1st - let's just get this out of the way - there is no such thing as constructive intent, the phrase you are looking for is constructive possession

2nd - the definitive case law on the subject is from the Thompson SCOTUS case and to paraphrase the decision is as follows: The burden of proof lies with the prosecution, so in the case of constructive possession the benefit of the doubt will be given to the defense and therefore constructive possession only applies to the case where there is no legal use for combination of parts other than the construction of a NFA weapon.

So if you have a short barrel and pistol (or frame/receiver) to use it on, or a stock and rifle (or receiver) to use it on, you would be good-to-go.

If within your pile of parts that could be used to create an illegal, unregistered SBR, is one part that could not be used in a legal configuration, you would have a problem.

ETA - if your pile of parts could not be used to create an illegal, unregistered SBR, (ie. you only have a barrel and a receiver with no other parts including other assembled firearms) you would be ok.