hi there ive renovated a few beach stocks and i found the trick to getting a good finish with beach was in the sanding.
basically don't try to sand the old stain back too much because first of all you will never get all the old stain out of the wood grain and also you will get a patchy looking stock (not very nice).
but use the old stain to your advantage i.e. leave the old stain in the grain.
then re-stain (i use dark coloured stains)
then what happens is the wood grain will be twice as dark as the rest of the stock then finish with Danish oil.
which in most cases depending on the stock gives an almost walnut type of look.
great