Bgile wrote:Both weapons use sabot, which is inert. It's unclear to me why a penetrating rod from a 30mm is going to be more destructive than one from a 20mm. In both cases the missile has to be hit to get results, and in both cases the missile will be destroyed by a hit.
Both used DU rounds although other types are available and I believe the ground mount phalanx does use an alternative round. However a hit isn't necessarily enough to destroy a missile. The theory was that if you did enough damage to the airframe the missile would miss. If that's the plan the more damage you do and the further out the more likely you are to be successful. One of the potential problems for Phalanx was that it might get an airframe "kill" at a range that simply would have little impact on it's effect on the ship.
It's also not obvious to me why you would want to mount a GAU-8 when for about the same weight and deck footprint you can mount a missile with several times the range.
CIWS systems are for leakers. You defintily want longer range systems as well but again some missiles are not easy targets for counter missiles.