I think that the easiest thing to do will be to repeal the '86 MG ban, and to then work on the '34 NFA. After all, prior to '86 anyone in an NFA state could legally go through the process and buy a brand new MG. It has been 19 years, and the only effect of the law was to enrich a few dealers and collectors. There are still something like 200,000 MGs out there (as opposed to approx. 100,000 only a few months before the ban), and none have been "taken off the street" because of it. Anyone getting a MG still must go through the background check, etc., and the rate of crimes with these guns is virtually nil (literally - isn't the only recorded incident of a crime being committed with a legal MG since 1934 one where a police officer committed the crime?).
I have the perfect name for the legislation that will get the ban repealed: The Machinegun Registration and Tax Act of 2005. We can pass it off as a means of registering MGs and bringing in more money to the fed.gov - what self-respecting lieberal or RINO can be against those things?
As to SBRs and SBSs, isn't that only a $5 tax? Not that I like the principal at all, but I'm much less ticked off about something that isn't banned and which is cheap to get if I'm so inclined, vs. the total ban on new MGs (with the resulting rise in prices of those few on the market). I'd really like a Tommy Gun, it looks cool and has a history, but I ain't paying many, many thousands of bucks for one. Ditto for many other guns - they've been made all but unobtainable for most people...which was exactly the point of the MG ban. Let's get THAT reversed.
Anyhow, in keeping with the subject of the thread, after 10 years or so of having new MGs registered and taxed there will probably be 500,000 to 1 million on the books. We can then go and say "See, there have been no crimes committed by those owning legal MGs. The criminals have disregarded the law and still commit crimes with illegally obtained guns, so getting rid of the taxation and registration will have no effect on crime."