When using the MK6 mortar aiming down the sight and using the arty computer yield different results with the same shot. Manually aiming tends to come up short while the computer is dead on even when using a pre aimed shot from the computer. This is occurring more regularly when attempting indirect fire.
In addition the mortar tends to damage itself and the operator with each shot. Though this tends to be fairly inconsistent
Drop mortar on runway
Set target on other end of runway
Place obstruction between
Fire shots from the arty computer, impact should be dead on
Fire the same set of shots from the manual sight without moving the gun
Shots should land short of target by around 100m or so
To reproduce the damage bug you simply need to fire the mortar repeatedly. I did it as a UAV operator (used UAV to spot shots) and getting onto the mortar rather than spawning on it.