Pin meters are a big disappointment. The problem is that you really
have to measure conductance, not conductivity, and that needs a
consistent arrangement of electrodes in the timber, not just a surface
contact. The only way to get any really useful measurements from one
are to use big pins and a slide-hammer to sink them repeatedly each
time. With that and a few bucks worth of electronic front-end meter,
then you're set. An FET front-end and moving-needle meter is easier to
stick a calibration scale to than a digital meter.
If you want rapid NDT measurement, go for a loss factor bridge (still
fairly easy to build, if you understand electronics at the "amateur
On the whole though, measure air humidity and allow time for your
timber to equilibriate. It's much more accurate (and useful) unless you
expend serious effort on your moisture meter.