Combat Shooting is unique in 3 ways.
- It only exists in the PC version of Wasteland.
- It can only be learned at character creation.
- It does absolutely, precisely nothing.
In the Mercenaries, Spies and Private Eyes PnP RPG by Michael A. Stackpole, on which the gameplay mechanics in Wasteland were based, Combat Shooting increased the player character's ability to hit with shots after the first with a burst/autofire attack.
It has no effect in the game.
The skill can be learned from Killing for Morons found in a bookcase at the Bastion of Faith, near Fealty Mayweather. The skill has a very specific effect: Increases the critical chance by 11% per every point above 1. As the book adds full ten skill levels, maxing it out at 99%, a character with Combat Shooting will make a critical hit with every single shot they fire, as long as the weapon they use has any kind of critical chance at all.
Perception level 10 is required to "discover" the hidden panel in the bookshelf. Else although you can still examine the bookshelf, you won't find the book, you will simply get message saying "you noticed a few books about weapon maintenance..etc".