Was rereading the LA Primer (insomnia) and I realized
that if you abandon a lot of the old assumptions,
(operators must survive, materials must be ready
asap from Hanford) a lightweight fizzle bomb is quite possible.
All you need is very high quality 239 without much
240 in it; this requires only a reactor, logistics,
and busy chemists. You risk premature det but
its worth it.

30 lbs of very special 240-free Pu plus a gun-design. Be or
no tamping -you trade off weight for yield.
The fundamental Pu problem of premature det
is only a problem if you need tens, not singles, of
kT. Some uses (eg, asym warfare)
work fine with a single kT of nuke.

One can only hope, for the freedom of the republic, that zero will be DC.