This is a specific reference to a lot of Browning firearms; one of the ways that Browning used to dry out their stocks was to stack the blanks in salt, which would draw out most of the moisture in them (but it would simultaneously draw some of the salt INTO the wood). Then, after the blanks were turned into finished stocks, that salt would corrode the steel where the wood touched. After this all came to light, Browning stopped using the process, but it's something you still have to look out for when buying a used Browning.