Lol, I was actually going to add that but decided it would be too pedantic if I said it myself.

I thought it had to do with physicists working off theoretical calculations finding precise values for the circuit and not realizing that components come in discrete values.

Cool, though I would assume the supercritical point would be a lot higher for Pu-242. I can’t imagine that anyone would have knowingly sold this kid a fissile isotope.