In the late '60s and early '70s there was a shortage of wood for stocks. Browning attempted to reduce the problem by speeding up the drying on some wood by treating them with salt !! Some owners found years later that the salt doesn't come out when they took apart the gun.
I suggest that you soak the stocks in fresh water for a few day though I don't think detergent will help. Dry them slowly without getting them above about 100 F .When thoroughly dry see how they fit the stock .If necessary scrape the barrel and receiver channel for necessary clearance . thoroughly coat the channel with a waterproof finish like polyurethane.
And Watson , bring your revolver !