I heard aiming fully increases your chances of hitting
No, seriously. A fully aimed aim circle has pre-accuracy-nerf shell distribution, whereas a non-fully aimed circle at any point suffers from the worse shell distribution chances within the circle.
With the long aim time of the 1-4, you might be tempted to fire just before being fully aimed. Using the serversided crosshair also helps with finding out the timings.
This might also explain why the T-100 for example is a pretty reliable sniper - It is aimed fully very quickly, negating the 0.4 accuracy (when maxed out).
This might also explain why the Grille and similar feel so shit - The aim circle is temptingly small yet not fully aimed when firing, hence suffering from "worse" RNG.
Or tanks at this point now have hidden hidden stats for this, which wouldn't surprise me given recent findings.