@Wwoodsroad
here is a thread for you, 40 mm Chalk rounds confiscated by ATF
f) Destructive device.--The term “destructive device” means
* * *
(2) any type ofweapon 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 ofwhich have a bore of more than one-half inch in diameter, except a shotgun or shotgunshell which the Secretary or his delegate finds is generally recognized as particularlysuitable for sporting purposes; . . .
Section 5845(f)(3) excludes from the term “destructive device” any device which is neither designed or redesigned for use as a weapon and 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
http://castboolits.gunloads.com/showthread.php?285208-40mm-Chalk-rounds-now-ruled-as-explosive-shells
Amazing, the tiny minds that populate the government goon squads.