The subject of plunging fire has been discussed. The heavy guns on most World War One battleships had only a maximum elevation of only up to 20 degrees.
Thanks for the info!
However, elevation data is available for all guns listed in the Grand Fleets rulebook, and was used to determine whether the gun was or was not capable of plunging fire.
Obviously, we can't be completely accurate without test-firing every weapon at range (which would be fun... ), but I am confident that we have accounted for the facts you present...