If you think the Hughes amendment can be "partially repealed" then why stop there?The next time we get a Republican (or libertarian) President and the GOP controls the legislative branch,
we ought to lobby for a bill that mandates that the 20" barreled M16 rifles be declared SUPRLUS and offered for sale, as-is, to any qualified buyer who is willing to do the NFA registration process and pay the NFA tax.
P.S. For those of you who are .223 machinegun owners whose guns would drop greatly in value if this were to happen, well, sorry, but it's for the greater good. I say flood the market with transferable M16's for a dozen years.
Post-PS: Naturally, this new law would be a partial repeal of the 1986 law that cut-off the transferability of post-May, 1986 full autos.