Which firearms are regulated under the NFA?

(1) a shotgun having a barrel or barrels of less than 18 inches in length;

(2) a weapon made from a shotgun if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 18 inches in length;

(3) a rifle having a barrel or barrels of less than 16 inches in length;

(4) a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length;

(5) any other weapon, as defined in subsection (e);

(6) a machinegun;

(7) any silencer (as defined in section 921 of title 18, United States Code); and

(8) a destructive device.