The grenade shell has a safe arming distance of five to six 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 killfeed 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.
The radius of explosions vary between game. The explosive damage of Grenade Launchers are affected by Danger Close in Call of Duty: Modern Warfare 2 and Call of Duty: Ghosts, enhancing their effective range and damage, and cancels out Blast Shield. In Call of Duty: Modern Warfare 3, the radius was reduced significantly, with the lethal explosive radius of an uninjured enemy being about 1.7 meters (this was likely done as a measure to prevent the over-usage of grenade launchers, which was the case in Call of Duty: Modern Warfare 2). In every game since MW2, grenade launchers and explosives in general continue to be nerfed becuase of the massive amounts of explosives spam in that game.
In some games, grenade launcher shells will not explode if fired in the first 10 to 15 seconds of a round/game to prevent easy spawn-killing. However, it is still possible to spawn kill in this case with the direct impact.
The underbarrel grenade launcher is available to all assault rifles (except the AE4), and to the AMR9 submachine gun. The AK12 "Grenadier" and the AMR9 "Banger", "Noob Tube", "Pro Pipe" and "Royalty" supply drop variants have an integrated grenade launcher by default. The launcher has two grenades in total and cannot be replenished with Scavenger. Kills with the grenade launcher attachment will count towards the base weapon's challenges.
The explosives have very limited radius and damage within the explosive radius, making Danger Close very valuable.
On the AMR9, performing a Speed Reload will make the Grenade Launcher reload faster, increasing its rate of fire.
With the Grenade Launcher, there is a small delay between firing the grenade and the start of reloading the grenade. This delay can be shortened by pressing the corresponding reload button as soon as the grenade is fired.
The Grenade Launcher is very useful for completing strafe challenges on certain weapons, as boost jumping up in the air and killing someone with the Grenade Launcher will count towards said challenge.
The AMR9 - Noob Tube equipped with a Grenade Launcher
A kill with the M203 and GP-25 counts as a hip fire kill.
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 Call of Duty: Black Ops, the icon is of a GP-25.
The Grenade Launcher attachment is listed as a secondary weapon on the Call of Duty ELITE Create-a-Class menu.
In the Zombies mode of Black Ops, there is no minimum distance that the grenade must travel to explode; this can lead to shell shock if used at close range. In Black Ops II however, there is a minimum distance.
In Call of Duty 4: Modern Warfare, when firing the grenade launcher, the vapor trail left behind by the grenade flying through the air is a zig-zag pattern, and it seems to fly faster than grenades launched from a grenade launcher in newer games. In Call of Duty: Modern Warfare 2, the vapor trail arc is more round and it seems to fly slower. The same effect is present with further titles, as the zig-zag effect is not in them. This can throw off aiming if the player is used to the smoother vapor trail of newer games.
In the extended mission of "F.N.G.", it was stated that the grenade launcher cancels out when fired too close for "safety" purposes.
If the 'Infinite Ammo' cheat is activated in the campaign, the grenade launcher becomes fully automatic. The M203 on the M4A1 will fire at 200 RPM, and the GP-25 at 120 RPM, whereas the M203 on the M16A4 will fire significantly faster at 600 RPM.
There were originally three more grenade launchers: AG36(G36C), HK79(G3) and FN EGLM. The names can be found in localized strings.
In the first 15 seconds of a match, 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 the campaign, in third-person, non-playable characters hold their weapon as if it does not have an Grenade Launcher, but in multiplayer and Zombies, they do.
Using the underbarrel grenade launcher replaces the regular ammo counter with its own, unlike in previous games.
The damage output 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.
Oddly, 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.
When playing a 1980's campaign mission, using the underbarrel grenade launcher doesn't replace the regular ammo count with its own, but it does in the 2025's missions, as well as in multiplayer and Zombies.
When using Fast Mag, the Grenade Launcher will reload faster.