How about the King Tiger one shot Vet 3 AT guns and Rifles?
The KT costs an absurd amount of fuel. Does not shoot across the entire map from inside your base sector. And is counter-able without access to doctrinal abilities (at least as USF - Sov might have a harder time without access to call-ins, but once again this goes back to their broken tech system which I keep harping on). Plus the KT is slow, you can hear where it is going to be before it gets there, and you have a LOT more time to react/prepare.
Yes the KT is strong, but it is far from game-breaking.