Yah. A VF-0's GPU-9 35mm gunpod held 550 rounds of ammunition. Quite a difference compared to the SV-51's 150 rd. capacity Gsh-371 55mm gunpod. And yes, a 55mm shell is quite powerful. Although, the VF-25 sports a 58mm shell.
If you understand how a P90's magazine works, then the idea isn't far off from how VF magazines work. Although, VFs probably use a mechanical feeding system, but the point is still the same, it's a non-traditional method of a belt/drum system. Look at the Calico M960 SMG as another example.