"Fragmentation grenades are very effective anti-personnel devices. The high explosive charges reduce their metal casing to flying fragments, causing considerable blast damage. Though they're ineffective against armoured vehicles, they are extremely useful for clearing out entrenched infantry positions."
The Mk 2 Grenade is issued to the Americans. In Call of Duty and its expansion pack Call of Duty: United Offensive, all grenades are statistically similar. They have a damage range of 250-10 in single-player, and 120-5 in multiplayer, with a fuse of five seconds. They also have a melee attack that deals 50 damage, with an animation similar to a pistol whip. The maximum number of grenades one can hold is 10, although in practice this only occurs in single-player. In multiplayer, grenade distribution is determined by the weapon the player spawns with. Those equipped with a Springfield receive one grenade; those with the Thompson or BAR receive two; and those with the M1 Carbine or M1 Garand receive three. Importantly, in Call of Duty, players cannot be shellshocked by grenades.
In Call of Duty: United Offensive, the damage and the maximum number of grenades stays constant, but a few changes are enacted. Players can be shellshocked by grenades. Grenades also have the ability to be cooked, where the grenade is armed but kept in the player's hand so that the fuse is shortened when thrown. Grenade distribution is totally changed as well; instead of being determined by the weapon equipped, it is determined by rank. Privates spawn with one grenade, Riflemen with two, and Platoon Sergeants with three.
This weapon is the American grenade of choice. It is uncommon, and is exactly the same as the other grenades. It cannot be cooked just like the other grenades in the game, but can be held in hand (fuse doesn't change).
"Hand grenade often referred to as a "pineapple" because of its cross-hatched exterior. Pulling the pin and releasing the spoon allows some time to "cook" the grenade before it explodes."
— In-game description
The Frag Grenade (listed as Mark II A1 "Pineapple" in the bonus materials) returns in Call of Duty 3. It is the standard grenade used in the American campaign, and is used by the Allied team in multiplayer. There is an on-screen counter which notifies the player as to when the grenade will explode. In multiplayer, it performs identically to the Steilhandgranate.
In campaign, the player can carry Mark II grenades and Steilhandgranates in the same slot (up to six lethal grenades, both models combined).
In Call of Duty: World at War, during the campaign, the Mk 2 is the standard fragmentation grenade for the United States Marine Corps. The player will always have four at the start of an American mission, but they almost never are found in the actual level to be picked up.
There is a perk called Toss Back that allows these grenades to be picked up and have their fuse reset so they can be effectively thrown back.
The Mk 2 Grenade appears in Call of Duty: World at War (Nintendo DS) as one of the two grenades available in game, the other being the German Stielhandgranate. Though meant for use by Americans, the Mk 2 is used by the Red Army and the Imperial Army as well. It also differs slightly in appearance compared to the console versions, sporting a gray color scheme as opposed to a green one.
In the campaign, the Mk 2 is a starting grenade for the USMC, the SAS, and the Red Army. The player always starts with five grenades, the maximum, but can resupply from grenades found on the bodies of enemies or from ammunition crates. As mentioned before, the Mk 2 is also used by members of the Imperial Army and the Red Army.
In multiplayer, the Mk 2 is used by all factions with the exception of the Germans, which use the Model 24 Stielhandgranate. Unlike multiplayer on the consoles, all players are equipped with five Mk 2s (or Stielhandgranates for the Germans) when they spawn. Though grenades cannot be resupplied from the bodies of enemies or from ammunition crates, the five provided grenades encourages grenade spamming.
The Mk 2 Grenade is used by all allied divisions depending on what kind of grenade is picked up. It shared the appearance of its Call of Duty: World at War counterpart. It can be cooked for six seconds before exploding and killing the player. Sometimes even cooking and then throwing after four seconds can still kill the player. It is advised to cook the grenade when clearing out a fortification as the enemy can attempt to throw back the grenade. On some levels, cooking grenades is best used as an unexpected enemy attack that happen at random times, which renders primary and secondary weapons a poor defense, requiring for the player to use explosive weapons.
A Frag grenade about to be thrown. Note the six second timer represented by six red lines around a white dot.
Grenade Indicator and Throw-back grenade indicator in Call of Duty: World at War: Final Fronts.
In the campaign, the Mk. 2 Fragmentation Grenade is the only grenade available to use and can only be resupplied at ammunition crates and dropped by some enemies. The player can have up to five grenades maximum.
"Lethal Fragmentation Grenade 6 Meter Blast Radius, Long Throw Distance Hold R1 to cook grenade."
— Additional info
In multiplayer, if a player has equipped the Mk 2 Fragmentation and is on the Axis Powers, the player will instead be given a Stielhandgranate instead. However, if the player is on the Allied Powers, they will be given the actual Mk 2 Fragmentation grenade.