This is the schtick to ignore cover.
A true master need not see his target for his missiles to fly true. With this schtick you can ignore modifiers for visibility, cover, obstructions et al. You can shoot in complete darkness, at invisible opponents or through thick fog or nauseous fumes with no penalty, though you must know they are there and can still stumble when groping around in the dark. If you miss, you may still hit the cover, which is important in the case of human shields and the like.
You can ricochet a bullet to go around a corner. Each bounce and the final target gives a -1 AV penalty, so one bounce would be -2, two bounces -3 and so on. You can thus target people without actually pointing your gun at them. Great for the Harvey Oswalds and Robocops among us.
If your targets are wearing hard armor or you do something like bounce the bullets off their rifles while disarming them, you can even bounce a single shot between several targets rather than off walls. This works like a normal multi-target stunt except that you save some ammo and are a lot more elegant.
Zen Marksmanship does not work with Autofire.