APS displays at least on the visual surface the wrong AP and damage number.
For this instance the shell should be 29,359 damage and 72 pierce. Instead it advertises a variance of about 50 damage and the wrong pierce give or take .1
This makes rail have RNG per shell instead of a realistic predetermined ap and damage.
Because kinetic shells (at least advertise) that their kinetic damage/ap don't reduce with speed until it's out of range, the calculation should always accurately do it's advertised stats unless disturbed.
Gunpowder isn't affected by this issue.