WD-40, although I don’t use it on my firearms I do know the it sinks to the bottom of a spot of water. Water floats on top off WD-40 water displacing water is what the WD stands for. It behaves the opposite of normal oil.
To remove water from inside your barrel pour in a bit of 99% alcohol, it will absorb the water and accelerate it evaporation. Like gas line anti freeze that absorbs water in gasoline it all then burns up in the engine.
So either WD-40 or alcohol works to remove water from barrel steel inside or outside.
I’m sure squirting in brake cleaner via a high pressure aerosol spray can would work too maybe even better considering the light specific gravity of the fluid.
Paste wax will lift off the surface it’s applied to if water is splashed on it that’s thats how white rings are made on a coffee table, always put your cold sweating beverage container on a coaster so it won’t lift the wax finish.
Also wax is a very poor anti rust product.