This subtitle does not apply to a short-barreled rifle or short-barreled shotgun that is: an antique firearm as defined in § 4-201 of the Criminal Law Article; a device designed or redesigned for use other than as a weapon; a device designed or redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device; or a firearm that cannot: discharge a projectile by an explosive; and be readily restored to a firing condition.