The importance of the grease

[Seaspriter]

wet spot beneath a steel filing cabinet left over time resulted in a "slight discoloration" of the floorboards, or what was in reality a big black stain.

There is a big difference between the black stains from iron interacting with tannins in wood and "oil rot" which is a degradation of the wood fibre.

Iron stains in wood can be diminished with oxalic acid bleach.

Oil rot requires either the cutting out of the wood, or the extraction of the oil from the spongy wood, followed with an epoxy soak (like the WEST system). I haven't used the epoxy soak on an old gun, just oil boats and furniture. Has anyone tried this?