AP vs Bunker/Pillboxes

[Griefbringer]

At close range, lucky shot with AP ammo can hit a weak spot, resulting in a bonus to the penetration.

Also, bunkers can take damage also from hits that do not penetrate, representing a lucky bullet passing though a slit and hitting somebody inside. Thus it is possible to take out bunkers with small arms fire - though it will require a whole lot of shooting.