If there is any chance of the water being salt, brackish or polluted, the best thing to do first is a lengthy soaking in clean fresh water, with the wood removed. Then as water can stay trapped in odd crannies, heat it gently to just above 100 centigrade in an oven. The water has got to be gone then. If there are plastic parts that can't be conveniently removed, heat it just a shade hotter than you enjoy handling, on a radiator for example, for a longer time. After that do whatever you would do about oiling that particular kind of gun.