The less filler a shell has compared to it’s caliber, the less blast damage but more fragmentation it creates.
A russian hef round will produce lots of fragmentation and will probably hit a lot of stuff at once systems, which may include crew, pilots, traction of control surfaces, control surfaces, oil system, engines, fuel tanks, etc . But it won’t make much of a difference to spars or tails.
Stuff it with filler and you end up with worse ballistics to start first, very concentrated damage but now if you want to knock out modules you need to strike directly, however, 1 strike and that is gone, also includes spars. BUT YOU NEED TO CONNECT DIRECTLY OR VERY BUT VERY NEAR.
Both these shells are slowed down a lot or stopped completely by armor or any survival system like EFS or self sealing tanks, say hi to AP, fly in and out and punch a hole into that module with ease to take it out, can reach to juicy insides behind that tail or armor plate.
What? Your plane has more than 2 cannons? No worries! The effects of having multiple cannons are felt! La-7B-20 and Yak-3P are actually +0.3 BR material compared to La-7 and Yak-3, or Spitfires with 4 cannons instead of 2 actually feel different, or Fw-190 As actually somewhat feel incredible firepower, Yak-9T can stop being overtiered ass for a super exact example.
Currently it is “I have 20mm cannons”.
-What model?"
-idk.
-What amount?
-Idk.
-What filler?
idk.
-What pen?
-idk I just have 20’s
-What firerate?
-Oh around 700rpm (it was 850)
-What belts?
-The one with more yellow
Or
-You have decent armor?
-Idk, I don’t really feel it, maybe my airframe is just heavy
This will scale up by caliber, we have 23mm that basically will outperform every 20mm shell no matter the filler it will be a more powerful 20mm, at every relation of Explosive/Case it will fragmentate more and deal more blast damage
And the last step will be +30mm and up which will be complete plane obliteration, deserved because 30mm are very fussy to land.