Browning for decades would replace salt wood under warrenty, but I believe they stopped this several years ago. The salt I don't believe will cause a problem without the presense of moisture. Guns not hunted with often don't show symptoms even if they contain the salt.
Your stock may have well been replaced. I would test it to be sure. If there is salt and no real metal symptoms, you might try something I have considered in the past. If you can seal the salt away from the metal, there would be no effect. I have often thought about sealing the metal and wood in the inletting to create a barrier. There are laquer coatings for metal that can seal the metal surfaces. For the wood, a couple of good coats of a saturation epoxy for boatbuilders, such as Gudgeons or System Three would stop the migration and shouldn't ad enough thickness to affect the inletting.
If you decide to swap for another factory stock, check the new wood before starting.
