I truly believe is 2 must have special rounds that automatically used every two tree shots and when it fired and hit it would delete enemy tank turret it special animation during wich turret goes up split in two parts or more with loud boom sound killing all only ENEMY infantry within 2 screens including buildings
If you play with mods you can still spawn the removed units, they are still in the game. Try the more units mod or even just the cheat mod and spawn them.