[PlasmaKrab]

Regarding weapon slots, there are ways to deal with the shortage if you're ready to coope with some minor inaccuracies.
For instance TMGs and CMGs are often redundant.
Also, AP and Sabot ammo give two main anti-armor ammo variants to some tank/AT guns and autocannons, which can then be applied to more units over time. One good example of that is the early 105 and 125mm tank guns. If you consider that the AP range increases with the technology level, you can use the AP and sabot slot for two different rounds (e.g. APDS and APFSDS), which would not be used simultaneously in the same unit, but can end up figuring two "weapons" for different dates.
These methods have already been used in some cases IIRC.