Ammunition

There are various types of ammunition featured in the Counter-Strike series, all of which have their own unique properties (damage, armor penetration, cost, etc.) which in turn also effects the efficiency of the weapons that fire them. Broadly, ammunition can be divided into pistol, rifle, shotgun, and heavy (Counter-Strike: Condition Zero Deleted Scenes only) categories. While there are many types of pistol and rifle ammunition, the only shotgun and heavy ammunition available are the 12 Gauge shotshells and 66mm respectively.

The simplest way to gauge the power of any particular ammunition is to observe the amount of energy it generates (in Joules) as stated in the VGUI menus. On a side note, if a cartridge is listed as AxBmm then A denotes the width of the bullet and B the size of its case in millimeters. If the notation is .XYZ, then it is the width of bullet expressed in 1/100th of an inch.

General

Ammunition originally required players to purchase them with money, adding another layer into the game's economy management.
In Counter-Strike: Source, players no longer need to purchase ammunition. Players automatically receive full ammo (loaded and backup) for all their weapons when a new round starts. Players will also always receive ammunition immediately after picking up a weapon, unless it was already empty. When out of ammo, running back to the buy zone and purchasing ammo for a primary weapon will get you another supply of ammunition.
- If the player drops a weapon, its reserve ammo will also be discarded alongside with the weapon itself, unlike previous games where the player can keep the ammo of that weapon even when dropping it.
- However, should the player wields a primary and secondary weapon that shares the same ammo, the player can keep the reserve ammo.
Prior to Global Offensive, if a player equips a primary weapon that shares ammo with his secondary weapon (MP5 with Glock 18 for example), the player will draw ammo from a single ammo pool. While this can make it easier to find ammo (in older games), the player's reserve rounds can easily deplete if ammo conservation is not taken into account.
In Counter-Strike: Global Offensive, all weapons come with their maximum ammunition when purchased and are refilled when the next round starts (like Source). However, additional ammunition cannot be bought once a round starts. This is because many weapons are balanced by having a low ammunition reserve (USP-S, CZ75-Auto, P250 etc). Ammo sharing between weapons is also disabled.
The caliber of a weapon can be viewed in the buy menu until Global Offensive. However, Global Offensive still includes references to weapon calibers in game files.

Pistol ammunition

Pistol ammunition is mainly used by the secondary pistols and submachine guns. Generally, pistol ammunition is cheaper than rifle ammunition, is low powered (except the .50 AE) and has poor armor penetration (except the 5.7x28mm). Pistol ammunition is typically shorter and fatter than rifle ammunition and depends upon the size of the cavity it makes to disable a target. Due to its low velocity, it has poor armor penetration, but is easier to suppress.

9mm Parabellum

It is the most common pistol caliber found in the game and in real life. Its main advantages are its low cost and high ammunition capacity of the sidearms chambered in it. On the downside, the 9mm does low damage and has poor armor penetration.

It is the starting ammunition the Terrorists spawn with. Terrorist players automatically obtain the Glock-18 and can carry a maximum of 120 spare bullets of the 9x19mm, with the exception of the CZ-75 which only allows 12 rounds in reserve.

While the 9mm ammunition is widely recognized as low-powered, the Tec-9 and CZ-75 can perform instant-kills by scoring headshots, even if the target has a helmet on.