Originally Posted by The_Real_Hawkeye
I sure thought over .50 caliber cartridge firearms were classified as destructive devices, apart from shotguns.


Read all the way to the end (emphasis mine):

§ 479.11 Meaning of terms.

Destructive device.
(a) Any explosive, incendiary, or poison gas (1) bomb, (2) grenade, (3) rocket having a propellent charge of more than 4 ounces, (4) missile having an explosive or incendiary charge of more than one-quarter ounce, (5) mine, or (6) similar device; (b) any type of weapon by whatever name known which will, or which may be readily converted to, expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore of more than one-half inch in diameter, except a shotgun or shotgun shell which the Director finds is generally recognized as particularly suitable for sporting purposes; and (c) any combination of parts either designed or intended for use in converting any device into a destructive device as described in paragraphs (a) and (b) of this definition and from which a destructive device may be readily assembled. The term shall not include any device which is neither designed or redesigned for use as a weapon; any device, although originally designed for use as a weapon, which is redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device; surplus ordnance sold, loaned, or given by the Secretary of the Army under 10 U.S.C. 4684(2), 4685, or 4686, or any device which the Director finds is not likely to be used as a weapon, or is an antique or is a rifle which the owner intends to use solely for sporting purposes.

Forgive me my nonsense, as I also forgive the nonsense of those that think they talk sense.
Robert Frost