Grenade Launcher

A Grenade Launcher is a device that shoots a grenade. These can be standalone launchers, such as the Thumper or China Lake, or attachments, such as the M203. Grenade Launchers appear in several forms throughout the Call of Duty series.

The grenade shell has a safe arming distance of 5–6 meters and will not detonate unless it has traveled this distance before hitting a surface. Thus, shooting at nearby walls, ground or ceiling will simply cause the shell to bounce harmlessly away. This makes using a grenade launcher at close range very difficult. However, the shell will kill if it directly hits another player, and in turn the direct impact kill feed icon will be displayed. It is possible to even score a direct impact kill on multiple enemies with a single shell, though this is very rare and requires a high amount of luck.

In some games the grenade launcher has restricted damage at the beginning of each round. This was likely done to make spawn-killing harder.

Call of Duty 4: Modern Warfare

 * GP-25 (Underbarrel, AK-47 only)
 * M203 (Underbarrel)
 * Mk 19 (Shock and Awe only)

Call of Duty: Modern Warfare 2

 * M203 (Underbarrel)
 * GP-25 (Underbarrel)
 * Thumper

Call of Duty: Black Ops

 * M203 (Underbarrel)
 * GP-25 (Underbarrel, AK-47 and Galil only)
 * Tishina (Underbarrel, AK-74U only)
 * China Lake

Call of Duty: Black Ops DS

 * M79
 * M203 (Underbarrel)

Call of Duty: Modern Warfare 3

 * M320 (Underbarrel on most weapons)
 * M203 (Underbarrel, M4A1 and M16A4 only)
 * GP-25 (Underbarrel, AK-47 only)
 * M320 GLM (Stand-alone variant)
 * XM25
 * Sentry Grenade Launcher (Survival Mode only)

Call of Duty: Black Ops II

 * M320 (Underbarrel on most weapons)
 * War Machine (Scorestreak)
 * M203 (on FAL and M16 in Campaign)
 * GP-25 (on AK-47 and Galil in Campaign, and AN-94 in all modes)
 * MM1 Grenade Launcher (unlockable for use in Campaign)

Call of Duty: Black Ops II
The Grenade launcher is a weapon attachment available for all assault rifles and is unlocked at weapon level 16. The grenade launchers are the M320 for all weapons except the AN-94 which has the GP-25 equipped. The grenades do not resupply with Scavenger as the blue packs do not drop by explosive kills and the packs obtained by gun kills do not resupply the grenades. It is still possible to get direct impact kills. Flak Jacket makes the grenades less effective as an enemy can take both of the grenades and still live.

Zombies
The Grenade Launcher appears in Zombies mode on Assault Rifles when Pack-a-Punched more than one time. The Colt M16A1 is an exception though, as Pack-a-Punching it one time will equip it with a M203. The Grenade Launcher operates similarly to its Black Ops counterpart, dealing high damage within a decent radius. On higher rounds though, the Grenade Launcher will begin to create crawlers, which can be considered as good or bad. Either way, the Grenade Launcher can be viewed as the best attachment for "modern" weapons due to granting the player with extra ammunition.

Trivia

 * In Call of Duty 4: Modern Warfare, the extended mission of F.N.G., it was stated that the grenade launcher cancels out when fired too close for "safety" purposes.
 * All grenades fired by grenade launchers are modeled the same (in the Modern Warfare series). This can be observed by looking at grenades that didn't explode.
 * In the first 15 seconds of a match in Call of Duty: Black Ops, any grenades from a grenade launcher will never explode. This was done to prevent using the grenade launcher to kill the enemy team quickly upon spawning, as they are naturally stacked up.
 * In Call of Duty: Modern Warfare 2 and Call of Duty: Modern Warfare 3, the player can complete a challenge called "Ouch" by killing someone with the grenade's direct impact. This will result in the title "Noob Tuber", a reference to the aforementioned derogative against players who use this attachment.
 * In Modern Warfare 2, when using Scavenger, the grenade has to be loaded to pick up another grenade. There are two slots for the grenade launcher: one that's loaded and one that is in reserve.
 * It is possible to get a headshot with a grenade from a grenade launcher.
 * The Modern Warfare 2 Create-A-Class picture lacks a trigger-guard.
 * If the 'Infinite Ammo' cheat is activated in the campaign mode in Call of Duty 4, the grenade launcher becomes fully automatic. The M203 on the M4 Carbine and the GP-25 fire with approximately 250 rpm, but the M203 on the M16A4 will fire significantly faster at approximately 600 rpm.
 * Any kill with the Grenade Launcher counts to the gun's total kills. The same goes for the Masterkey Shotgun, Flamethrower and the Tactical Knife.
 * A kill with the M203 and GP-25 counts as a hipfire kill.
 * In Call of Duty 4, there were originally three more grenade launchers: AG36 (G36C), HK79 (G3) and FN EGLM (F2000 or SCAR). The names can be found in localized strings.
 * In the Modern Warfare series, the Create-A-Class icon is of a M203 (except for the AK-47 in Modern Warfare 2), where as in Black Ops, the icon is of a GP-25.
 * On the FAL in Modern Warfare 2, the grenade launcher is misspelled as "Grenade Laucher".
 * In Zombies, there is no minimum distance that the grenade must travel to explode. This can lead to shell shock if used at close range.
 * In Modern Warfare 3, the under barrel grenade launcher used, for the first time, replaces the regular ammo counter with its own.
 * The damage output in Modern Warfare 3 seems to have been lowered for balancing purposes and Recon tags. Kills by the grenade launcher now usually occur by direct impact, close proximity detonation, or killing an enemy with low health.
 * The Grenade Launcher attachment is listed as a secondary weapon on the Call of Duty ELITE Create-A-Class menu.
 * Oddly, in Modern Warfare 3, there is no killfeed icon for the Grenade Launcher. Kills with it show up as the gun it is attached to. The same applies to the Shotgun (Attachment).
 * In Call of Duty: Black Ops II, there is a small delay between firing the grenade launcher and it actually firing in-game.
 * In Modern Warfare 2, there is a odd camo changing glitch that occurs when the player has two of the same weapons equipped with a grenade launcher, different optics and different camos. If the player switches to their grenade launcher, the camo will alternate between the two camos. This works with the shotgun attachment, but both guns must have the same underbarrel.
 * In campaign, in third-person, NPCs hold their weapon as if it's doesn't have an Grenade Launcher, but in multiplayer and zombies, they do.
 * Most CoD players dislike this attachment, often calling it "noob tube".