Thanks to the thread "M8 Greyhound Reload Times", a discrepancy was found in the three different Panzer IV main gun reload times:
F1 = 6 sec (7.5cm KwK 37 L/24)
F2 = 5 sec (7.5cm KwK 40 L/43)
H = 6 sec (7.5cm KwK 40 L/48)
Seeing as how the F2 and H fired the same cartridge, and the F1 had the smaller stubby shell more like the US M4/75mm, I'd think if HTC wanted to give credit to the F1 for having an easier go at reloading I could see why. However, currently the F2 has a faster reload than the F1 and H which is a bit out of the "sounds logical" line.
Not sure if this was an over-sight, error, etc.