All those up popping threads about different ammunition and damage values gave me an idea to resurrect this topic.
Hello my name is Karl and I like my "BT" designs to be functional - so when you say you put a 5 rifles and 5tons of ammunition in that 25t vehicle that should not be larger as a BMP - a Karl should pop open in your mind and ask you - serious?
anyhow - below you see the "third" attempt in making stuff understandable.
I have done some more work in the mean time - unfortunately another data crash destroyed some other files, i would like to have more work but before more topics pop open... here some "findings".
BT damage is very abstract, however, you have a common determinator especially when talking about shells - a AC2 shot is ~20kg for 2 damage. This translates great in the good old M1 90mm, as German, I would, of course, prefer the 88mm but that's not so important. The whole cartridge for both should be near 20kg. Muzzle Energy for both somewhere near 4 MJ. When you put some "sicfi" aspects like a more powerful propellant, electrothermal ignition of this propellant you might get a Muzzle Energy of maybe
7-9 MJ - for a single 20kg shot. Doesn't matter if you deliver it in a single round or several smaller but in the end of the day - you need to put
x-many round with a sum of
y-MJ with minimal dispersion into an enemy vehicle. When your 3 57mm rounds of your AC2 hit the target all over the place you deal no damage that you build on.
(Based on the assumption that today's ceramic armor shatters after the first hit but thanks to backing material keeps 99% of its protection. So you need to shatter it again and destroy the backing material by explosives)
When you use less high-tech propellant you might have lighter rifles but you need more weight per shot. So for example to get the 9MJ of an 20kg "AC2" you might need a 50kg shot of a larger caliber.
When you use this baseline you can have different ammunition calibers - even explain the difference between the Light ACs and the regular ACs.
for example - the drum of the defiance ac 5 of the Zeus - 75mm next to the 135mm rounds for the Napoleon Light AC 5... (bot ammunition storages weight a ton)
here are some of the third rework of AC ammunition:
a 90mm Full Bore CTA cartridge (shell is similar to the Raufoss MP)
a saboted 140mm with a 90mm shell,
a 140mm LBX round (a base bleed shell with payload)
a 90mm Ultra AC shell (using lighter ammunition for higher RoF that peepers the target with lots of darts)
this also explains why ammunition can not be interchanged.
TLDR;
high powered ballistics consume ~ 10kg ammunition weight for 1 damage
low powered ballistics consume ~ 18kg ammunition weight for 1 damage