Does AP ammo actually have an effect?
I didn't notice a difference between 5mm AP and JHP when using an assault rifle. I remember AP ammo was bugged in Fallout 1 or 2 (can't remember which right now) but when shooting.. anything, I didn't notice a difference in damage.
AP ammo does effect to armored NPCs and players, JHP is better in general usage.
It's always better use AP ammo against players, because they have armors.
Info5mm AP -> DR modifier -35%, decrease armor DR modifier by 35% (+ piercing)
5mm JHP -> DR modifier 40%, increase armor DR modifier by 40%