They weren't varnished or finished in boiled linseed oilicon which has chemicals in it to make it dry quicker. Like most military rifles of that vintage, the wood was treated with raw linseed oil. There was a dye powder that was mixed in the warmed tanks too although the AG42's I've had didn't appear to be stained at all. The wood was probably just dipped in a warmed tank of RLO and hung up to drip dry. Strip the varnish with the correct chemical stripper and then you can stain it to taste using alcohol based stain if you like. Then apply RLO and it will look perfect. RLO, not BLOicon will also take on a darker reddish tint with age.