Blackstone
Brigadier
@Blitzo
Dont forget that the rounds in that picture are suppossed to be ramjet powered. Hence the long range.
The payload options also look interesting. HE, Anti Personell as well as Anti Armor Cluster bomb units, fuel air explosive, and, most interestingly, small near-earth-orbit satellites, as well as anti-satellite payloads.
Bull wanted his gun to shoot payloads into space, originally. With this in mind, it gets really interesting.
The guns had limited tactical value, because they were fixed in place and easily destroyed. If Israel hadn't destroy them, then the US would have done so in the second Iraqi war.