Strongest in what sense? There’s basically no weaker 20mm round than the ShVAK and B-20 FI-T shell weighing just 96g with merely 4.13g explosive filler. Well, there’s the German counterpart and the Ho-5 firing and even lighter shells with 4.53g filler.
Larger 20mm shells have at best 10-11g explosive or explosive-incendiary filler.
It’s actually not 100%. Even when a surface turns black.
I tested it quite extensively, firing at IL-2s with a single ShVAK.
If you hit all over the place you can hit them 5-7 times without much effect.
Sometimes you one shot a wing or tail but often it requires two hits in the same area.
Then again, it switched my ammo from tracer to some other belt. So sometimes it was an API hit.
No, that’s FI.
But thats only available in the stealth belt and only 1 out of 4.
It’s a bit odd that there’s more HEF in the belts as those were the pre-war shells, while the default belt has the newest shells.
FI-T didnt exist till mid 1942