Moisture in wood varies significantly so the traditional method of pins on the surface of the wood is not very accurate as you only have contact with the outer part of the log.
Bio Moisture Wood has been developed to give more accurate results.
Chainsaw
Pellets
Sawdust
This method takes a chain saw to the wood and the resultant pieces are measured. This gives you a sample across the whole wood which is much more accurate.
This method can also be used on pallets, wood pellets and sawdust.