[SampleMan]

I'm presuming that 100% of the projectiles will be guided. In anything but direct fire, the accuracy at beyond 20 miles would otherwise be unusable. At the top of the trajectory, the fins won't stabilize, as there won't be any atmosphere. That reentry is going to really throw off the accuracy without guidance, as the projectile is going to oscillate until it stabilizes.

It is very hard to jam a GPS receiver located above you that is obviously looking up. It could conceivably be intercepted with an ABM system, but that is going to require firing a few golden arrows at clay bricks. The enemy would quickly become depleted and saturated, while the ship's supply of ammunition would just keep flowing.

This could be a real game changing capability. Laser, IR, or radar guidance could make it a tremendous, long-range anti-aircraft weapon, although I'm not sure that those seeker types can survive the acceleration.

[Tallguy]

“I’m presuming that 100% of the projectiles will be guided. In anything but direct fire, the accuracy at beyond 20 miles would otherwise be unusable.”

Unless the primary use for all this velocity is to fire UP, as in at the re-entry stage of a Chinese carrier-killer ballistic missile. That wouldn’t necessarily need guidance, and if it did, it wouldn’t be using aerodynamic control surfaces.