The act of shooting through penetrable surfaces is commonly known as wallbanging.
Note that bullet penetration is distinct from armor penetration, although the two's effects on damage are stacked.
The amount of damage absorbed during bullet penetration is affected by three factors: the surface's penetration modifier, the weapon's penetration power, and how far a bullet must travel to exit from the object.
Each weapon has a different penetration power value which ranges from 0 to 300. A value of 0 means that that weapon will never penetrate any objects, while a value of 300 means it will penetrate harder surfaces for greater distances. The total number of surfaces any bullet can penetrate in a single flight is capped at 4.
Submachine guns, shotguns (except the Nova) and most pistols have low penetration powers (usually 100). The Desert Eagle is the only exception amongst the pistols, having a penetration power of 200. Rifles and machine guns have good penetration powers, usually around 200. Sniper rifles have the highest amount of penetration power which is usually around 300. Nova is only weapon that has penetration power of 0, meaning that it will not penetrate anything but glass.
Prior to Counter-Strike: Source, assault rifles, machine guns, sniper rifles, and the Desert Eagle were the only weapons that could penetrate through walls.
The penetration power value for each weapon can be viewed in the in-game buy menu.
Surfaces and Materials
Before Source, low caliber rounds were unable to penetrate unbreakable walls or props, such as breakable glass until it was broken or very thin wood. Thus, pistols (except the Desert Eagle), shotguns, and submachine guns should not be used for wallbang purposes.
The surfaces of objects you shoot through, and the materials they are made up, are related to the difficulty in penetrating.
When an object has a different entrance and exit surface material, the damage lost is calculated using the average resistance of the two.
A bullet loses some damage immediately upon making contact with the surface (a bullet with a lower penetration power value loses more) and continues to lose damage as it travels through the material. When a bullet loses all of its damage, it fails to penetrate through the material.
You can either spray or burst-fire your bullets. Spraying is fairly risky as it can waste ammunition (although it can make it harder for enemies to retreat from volleys of bullets). Meanwhile, burst-firing should allow users to conserve ammo but it can alert nearby assailants and they can avoid being killed themselves. If you suspect a large group of enemies behind a penetrable surface, you can spray bullets at the wall(s) separating visual contact between you and targets or burst-fire and aim at the head when you have sufficiently practiced.
The most preferred times to "wallbang" is when enemies have retreated and have taken cover behind walls or props. This is when you can continuously fire at them without being killed yourself (unless the enemy is implementing the same tactic). Moreover, this is often used when rushing at hiding enemies is not a good idea, especially if they're armed with shotguns or Zeus x27.
Take note that "wall-banging" decreases damage so rifles with high-penetration damage, such as the AK-47, should compensate this. If one is close to an enemy player, aiming for the head is advised to deal maximum damage.
In Counter-Strike: Source and Counter-Strike: Global Offensive, the radar will display enemies when your teammate(s) have visual contact with them. This will give a sight advantage for players who do not have direct sight on enemies behind surfaces.
In some maps, shadows may clip through buildings/walls. Players will often exploit this by wallbanging to eliminate unlucky targets. This depends on the user's graphical settings.
Bots almost never use wallbang tactics since they are not as effective as human players. This gives human players an advantage to shoot through penetrable surfaces without being seen by enemy bots.
- Some players may resort to cheating to reveal enemy players behind walls and other obstructions to score otherwise unlikely headshot kills, most notably with the AK-47 or the AWP.
- In Global Offensive, in addition to the headshot icon, a wallbang kill icon is present.
- Killing an enemy by shooting through other players (friendly or otherwise) or a grenade is also classified as a wallbang kill.
- Condition Zero bots will almost never perform wallbang tactics. However, some bots, such as Ping of Death, can wallbang if configured to do so.
- How does bullet penetration work? at Steam