That would seem to make sense Arlo, but the Firefly appears to be closer to the Tiger than the Panzer in terms of performance.
I'd have to look up the 75mm guns specs, but I do think that nobody would have used it if it were modeled with the 75mm, simply because of the Tiger. That is exactly what happened to the T-34 - it was almost literally impossible to kill a Tiger in a T-34 no matter what the circumstances were, so just the possibility of running into a Tiger kept the T-34 in the hangar.