Luger stock on a Form 1?

[Bill_in_VA]

Remember too, that unlike a machine gun wherein the receiver itself is both a firearm in and of itself and the machine gun, an SBR is only an SBR because it meets a specific set of criteria. If it doesn't meet the criteria it isn't an SBR. Moreover, since a stock isn't even a firearm it can't be registered as such.

In other words, an SBR needs to be a firearm, and a rifle, and fit a specific definition.

18USC CH44 921(a)(3)(A) and (B) define a firearm and 18USC CH44 921(a)(7) further defines a rifle as a firearm that is "... designed or redesigned, made or remade, and intended to be fired from the shoulder ..."

An SBR, is defined in 26USC CH53 5845(a)(4) as a rifle with "... an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length ..." and again in 18USC CH44 921(a)(8) in virtually the same terms: "... a rifle having one or more barrels less than sixteen inches in length and any weapon made from a rifle (whether by alteration, modification, or otherwise) if such weapon, as modified, has an overall length of less than twenty-six inches. "

QED, putting a stock on a P.08 makes it into a rifle by virtue that it is now designed and intended to be fired from the shoulder. With a barrel length of less than 16 inches and an OAL of less than 26 inches it is be definition an SBR.

HTH