>      The Haynes decision occurred just a few
> months before enactment of the GCA '68, which changed the
> laws sufficiently as to make the entire Haynes issue mute.

The Haynes issue became temporarily mute only because...

"...The provisions for requiring registration of existing 
(illegally possessed) weapons were removed from the NFA in 
1968..."

...quoting Bardwell's National Firearms FAQ, linked from
many many places; I got this from...

   http://www.concentric.net/~ldrennan/NFA_FAQ.TXT

To continue, Haynes is still active precendent and becomes
very relevant as soon as a registration scheme is required.
Haynes is important anytime pre-68-NFA-like registration is
instituted...

----------
"...Before the NFA was changed in 1968, as part of the Gun
Control Act of 1968, one could register unregistered existing
weapons, however it meant you were admitting to possessing an
unregistered weapon.  In fact the law required it, which was a
reason the US Supreme Court used in gutting the registration
scheme of the pre-68 NFA in Haynes v. US, 390 U.S. 85 (1968). 
(It violated the 5th amendment right against compelling
self-incrimination.)..."
----------

Cheers,

Mike Haas