A real pity nobody here actually have any knowledge on this subject, considering how many milsurp collectors there are on this forum heh. Good thing I did pick up a few tips from another forum, might as well paste them here for your benefit:
There are products to make soft and rotting wood hard but really nothing to make reg. wood harder.
One thing that you need to stop doing is putting gun oil on the wood stock. It will break down the fibers in the wood over time making the wood soft. Ust BLO, Pure Tung Oil, Toms 3/1 mix or Howard's Feed n Wax on your wood stocks and you can also p top coat of paste wax on them.
Check the stickies at the top of this sectino of the forum for a repair post on how to repair chips in your stock.
Possibly the polyurethanes, although not historically correct, have the ability to protect the wood better than the more correct BLO's and such. The wiping of oil onto the wood phenomena is something I've seen done a lot. My dad after cleaning a gun and wiping some oil on the metal, continued onto the wood. I was able to convince him this was a bad idea, citing the old guns you see that had been excessively oiled and stored in the butt down position with the black nasty oil stain area where the stock met the metal.
Thanks for pointing that out candyman, as the problem warrants more attention, as I think it's a fairly common misconception.
Mike
I ordered two more cans of the Tom's 1/3 mix on line last night, I love the stuff.