After 20 hours I still don't understand how manual aiming works

[VOLAND]

Yes, the idle animation impacts where the shot lands. Not only that, but the target continues to animate in slow motion after the shot is fired.

Anyway, the system is actually quite involved. If you are interested, it is covered extensively in the guide I was working on, with explanations from other players and the devs:

@VOLAND

Accuracy

Each weapon has an inherent accuracy depending on its effective range, defined as the range at which the weapon is likely to hit a human-sized target 50% of the time. The range is calculated in tiles. So, a weapon with an effective range of 20, will hit a human at a distance of 20 tiles 50% of the time.

Still not clear, right? Where are the hit chances expressed as a percentage?

There aren’t any. Usually you manually aim the weapon using the free aiming mode (though you have the option to shoot at the center mass of the target more often than not it will be a suboptimal shot). In the freeaming mode you use an aiming reticle, which is a small circle inside a big circle. The small circle is one quarter of the size of the big circle. Each projectile fired from the weapon will hit somewhere inside the big circle and there is a 50% chance that a projectile will land inside the small circle.