That AP is better than normal rounds in every single way contrary to statements made in changelogs and by devs.
Doing a little *clarification in the forum where nobody will see that you've said "well no, actually normal rounds aren't better than AP despite "doing more damage" and you should just use AP until we've re-coded the entire ballistics and armor system weeks/months from now" doesn't mean that you've kept the information open and the playerbase infomed.
Hence, this is what gets called an "open secret" or an "unwritten rule" and only people who are familiar with the game actually know that despite what the wiki might say, or what the changelog might say, normal M41 rounds are not worth using if you can use AP instead.
Part of this also comes out of a direct intention by the dev team to obfuscate solid numbers on what works and what doesn't work, presumably to prevent metagaming and optimization for the combat system - but in reality if you had a decently structured combat system this information wouldn't matter: Some things would be good at particulars that other things are not, simply due to how they work; e.g. shotguns work at short range but not at long range. This means you get people using shotguns, AND you get people using M41's. The numbers don't matter so much because how these weapons are used determines whether a player uses them.
The only thing the intentional obfuscation of numbers achieves is hiding what this thread is actually talking about right now: Things like M41 normal ammo being worse in every condition than M41 AP ammo, and while you can claim all you want that this isn't an "open secret" there has been a concerted effort by the dev team to stay away from telling players specifics about balance while only letting privileged people (e.g. friends, people in discord) have hints or facts on the numbers.
I don't really care/agree/disagree with how the dev team handles it. There's pros and cons, and it's not a big enough deal for me to kick a fuss about.
But acting like this isn't how it is and that the team is actually open about how everything works really got my goat here.