Here is the law in Texas:
§ 46.05. PROHIBITED WEAPONS. (a) A person commits an
offense if he intentionally or knowingly possesses, manufactures,
transports, repairs, or sells:
(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.
(f) It is a defense to prosecution under this section for
the possession of a chemical dispensing device that the actor is a
security officer and has received training on the use of the
chemical dispensing device by a training program that is:
(1) provided by the Commission on Law Enforcement
Officer Standards and Education; or
(2) approved for the purposes described by this
subsection by the Texas Private Security Board of the Department of
Public Safety.
(g) In Subsection (f), "security officer" means a
commissioned security officer as defined by Section 1702.002,
Occupations Code, or a noncommissioned security officer registered
under Section 1702.221, Occupations Code.
I don't think TEXAS state law differentiates between a post or a pre 86 machine gun, all that is required as a 'defense' is that it be regiwtered with the BATFE. Note there are some 'defenses' and some 'affirmative defenses.'
Federal statutes regarding machine guns are generally found in the Unted States Code and in the Code of Federal Regulations. Here is a link to some of the statutes:
http://caselaw.lp.findlaw.com/casecode/ ... 4/toc.html
The BIG DEAL is to have your paperwork in order. MACHINEGUNS ARE NOT ILLEGAL under federal law as long as you have paid the tax, have complied with all paperwork requirements and have passed the NCIC background checks and of utmost importance have had BATFE approve your paperwork. Some states trump federal law and prohinit possession of machine guns regardless of federal law, but that is a state by state deal and is not law in Texas.
Hope that helps.