The stock is dried out from years of just being in a gun safe or
such... I would remove the barreled action from the stock and
apply BLO (boiled linseed oil) to it. this will replenish the
moisture to the wood and will make it swell. I've done this to
many old military rifles and it works for the most part. It may
take a few different applications before you see any results.
Denny