linseed oilicon is hygroscopic.
A fancy word that means it absorbs water.

If you look at wood treated with linseed oilicon,
the dark areas are where hands have held the stock.
There are many ways to prevent the absorbtion of
water, wax is one, but the military wasn't wanting
shiny stocks on the rifles, they just wanted something
to protect the wood without being expensive or shiny.

I like to use tung oil on my stocks. I don't mind if they
are shiny!