(1) an explosive weapon;

(2) a machine gun;

(3) a short-barrel firearm;

(4) a firearm silencer;

(5) a switchblade knife;

(6) knuckles;

(7) armor-piercing ammunition;

(8) a chemical dispensing device; or

(9) a zip gun.

(b) It is a defense to prosecution under this section that the actor's conduct was incidental to the performance of official duty by the armed forces or national guard, a governmental law enforcement agency, or a correctional facility.

(c) It is a defense to prosecution under this section that the actor's possession was pursuant to registration pursuant to the National Firearms Act, as amended.

(d) It is an affirmative defense to prosecution under this section that the actor's conduct:

(1) was incidental to dealing with a switchblade knife, springblade knife, or short-barrel firearm solely as an antique or curio; or

(2) was incidental to dealing with armor-piercing ammunition solely for the purpose of making the ammunition available to an organization, agency, or institution listed in Subsection (b).

(e) An offense under this section is a felony of the third degree unless it is committed under Subsection (a)(5) or (a)(6), in which event, it is a Class A misdemeanor.