Dude, one barrage from a calilope is accurate as werfer. Min range werfer is lethal, hence min range calilope is also lethal but there are far more rockets. Whatever at gun that was there will be wiped guaranteed. Even if the at gun was able to get off a shot, your calilope can eat FOUR shots unlike a werfer.
It dies in 3 shots since the latest nerf it got, which brought it down to 480 HP as well as many other things, I guess you still think it's as strong as it was on release where it fixed a huge gap in USF's Arsenal and was worth having the Commander just in case you needed rocket artillery.