M319 Individual Grenade Launcher

The M319 Individual Grenade Launcher, more formally known as the Individual Grenade Launcher, Caliber 40mm, M319, is a single-shot, break-action explosives launcher used by the United Nations Space Command, specifically the UNSC Army. Due to its simplicity, ruggedness, and firepower, it has been a mainstay weapon in the UNSC Army since its adoption in 2263, and has seen action in several armed conflicts during nearly three centuries of use, with the Human-Covenant war as the most prominent. It saw use during the Fall of Reach.

Weapon Dynamics
The grenade launcher has two firing modes. The first launches a single grenade: after hitting a surface, the grenade detonates on impact with an opponent or after the time of a frag grenade's detonation, in which case the grenade will explode after bouncing off the ground once. The second firing mode shoots a grenade that explodes when the player wishes. This is performed by holding down the trigger, which fires the grenade but merely primes it; it will only explode after the trigger is released. This enables the player to lay a trap if the grenade is bounced properly into position, and essentially creates an explosive with a dead-man's trigger (a trigger that will go off once it is released, e.g. when the player dies). This function is also helpful if the player wishes to fire at targets that are farther away than the detonation timer would normally allow. Like the fragmentation grenade in Halo: Reach, a player will take damage if hit by the grenade when it is merely primed.

The weapon utilizes a break-action breech-loading system: after firing one round, the weapon must be reloaded, like many twentieth century shotguns.

Tracking System
The IGL also has a tracking function which is useful when trying to target enemy infantry or vehicles that are fleeing As long as the enemy is in range, and the targeting reticule is red (which is the indication of in-range enemies), using either firing mode will ensure a hit as long as the cursor remains on the enemy at all times, as the grenade will track the target.

This tracking function is especially true and especially useful for the Falcon variant in the Campaign level New Alexandria that possesses an IGL turret—the range is extended quite extensively and a player can shoot down Banshees using either the explosive grenade (which can literally track a Banshee across the level just like a target-locked SPNKR missile) or the secondary EMP blast that makes them plummet helplessly towards death.

The IGL's target-locking ability is much like the targeting mechanisms for both the Plasma Launcher and the Rocket Launcher, however the handheld IGL has a much shorter range than the respective heavy weapons, yet the grenades can easily be bounced in precise angular measurements to ensure lethal shots. The IGL turret, however, with its incredibly high rate of fire and debilitating power, has a higher potential for lethality and also retains the original aspects of the handheld grenade launcher—both manual and automatic detonation and the grenades are capable of bouncing in tactical angles to eliminate singular or multiple enemies.

EMP Function
Also, the grenade emits a form of EMP, similar to that of the plasma pistol, that can temporarily disable vehicles and energy shields, but only when used in the manual detonation mode.

Lethality
The Individual Grenade Launcher is a weapon of potentially high lethality, even in the hands of unskilled players it can be effective; however, it is believed to be more difficult to use than a Rocket Launcher, yet the two weapons retain the same aspects of splash damage that is capable of eliminating multiple foes. In a skilled player's hands, the Launcher can be a perfect asset in crowd control and especially when used in certain areas such as the spawn points in the Firefight maps Holdout and Glacier. As the IGL basically delivers modified frag grenades, the grenades themselves are similar to the throw-able Fragmentation Grenade in both dynamics of physics as well as properties of explosive splash damage that can be spread to a single enemy or a group of enemies. Overall, this weapon can be a valuable asset in both a team or when playing solo as it is one of the best weapons to use to dispel crowds and clusters of foes.

Pros & Cons
There are many pros and many cons to any weapon in Halo: Reach—such is the design that balances everything. The IGL is a preferred weapon for all heavy weapon specialists out there and its versatility is used with both skill and chance.

Pros

 * The IGL is very versatile and can be used for a number of operations and even quick improvised reactions and has an enormous potential for both the destruction of vehicles as well as enemies (both Spartans and Covenant alike).
 * The secondary EMP fire makes it undoubtfully easier for vehicle hijacking (Especially for aircraft or slow witted tank drivers).
 * Rate-of-fire-wise, the IGL can utilize even more EMPs than the Plasma Pistol (3 seconds of reloading between each shot versus 2 seconds to charge up and 4 seconds of cooldown after said shot).
 * Players skilled with the it can be a deadly force. A direct hit with a grenade will always kill another player instantly. If the player is good at "leading" his/her target, this weapon can be even deadlier.
 * It holds quite a full max load of sixteen grenades which can compliment the default 2x Fragmentation Grenade spawn count very well—providing, potentially, eighteen grenades at a player's disposal.
 * Weapons such as the IGL offer the ability to ignite other hazards nearby such as fusion coils, nearby grenades (both Plasma and Frag), dormant and damaged vehicles, etc. In some cases it is possible to actually blow a nearby vehicle up and have it land on or nearby an enemy to cause a Splatter.
 * When used in tandem with other heavy weapons, or even other players using the IGL, it can be an excellent method to quickly decimate an opposing force.
 * It can be used in traps as the grenade will not detonate if held down and can be hard to spot.

Cons

 * The IGL can be quite difficult to use and can take quite some time to get used to for some players; it is possible to perform many accidents with the IGL if one is not careful, as the grenades can bounce off of any object—whether it be a weapon on the ground, a crate, an angled doorway, etc.
 * The secondary EMP function of the IGL can be used even against friendly players, and can inhibit teammates by shooting an EMP blast at their own team's vehicle, or perhaps igniting a nearby grenade to cause an "accidental" betrayal.
 * If "Friendly Fire" damage isn't turned off in a multiplayer Firefight game, using the IGL can cause severe ruination to a team as it is quite easy to betray a nearby player and dwindle the precious pool of lives.
 * There is no situation in the campaign wherein this weapon becomes the best choice - every function it has is performed better by other weapons. The explosion from the round is weaker than a normal frag or plasma grenade, and much less powerful than a rocket. Also, the EMP is not strong enough to knock out even an Elite Minor's shields on normal difficulty, which a charged plasma pistol shot is easily capable of. Also, its limited ammunition, lengthy reload time and of course the fact that a charged grenade is uncontrollable while in flight, mean that this weapon is not the logical choice.

Trivia

 * When fired normally (without holding the trigger), the Grenade Round makes a quiet whistling in flight. When the trigger is held, however, the round will make a noise remarkably similar to a tea kettle whistling, possibly as a gameplay strategy to alert attentive players to its presence.
 * The Grenade Launcher has multiple nicknames among the fan community and Bungie alike, including "pro-pipe", a reference to the numerous grenade launchers in first-person shooter games, which have been collectively dubbed "noob-tubes".
 * The M319 IGL, having been developed in 2263, is the oldest known active service weapon utilized by the UNSC.
 * In the Beta, if a player fired the M319 and held the trigger until he/she died and someone else picked up the weapon, the player holding the M319 would take control of the dormant grenade.
 * The M319 bears a very close resemblance to the real-life Russian GM-94. However, their similarities are merely aesthetic, as the GM-94 is a magazine-fed pump-action grenade-launcher using 43mm grenades. The M139 also bears a close resemblance to the American Springfield Armory M79 grenade launcher in both aesthetic and functional fronts. The two are break-action launchers that fire 40mm shells.
 * When reloaded, the M319's operator does not extract any empty shell casing. This could mean that it uses a caseless grenade round.
 * The grenade has a very poor trajectory, traveling only 100 yards before hitting the ground (real grenade launchers can travel approximately 430 yards).
 * In the alpha build, the M319 has a red light on its side. This was removed later in the beta build, and re-appeared in the retail version when the grenade detonated.
 * The counter on the left of the weapon switches from "ARMED" to (very briefly) "LNKNG" just after launch, and then to either "IN AIR" or "LINKED" after the round is launched, depending on the firing mode; and finally to "BOOM!" upon detonation.
 * In first person a player can only look a total of about 70 degrees (+35 to -35) on the Grenade Launcher's reticule; clearly this being another 7 reference.
 * Sometimes if you kill an enemy in campaign with the Grenade Launcher your allies may compliment you saying words like "nice throw" as if you killed the enemy with an actual grenade throw.
 * If a player fires the IGL in EMP mode that comes near an enemy or group of enemies the number of enemies near the grenade is displayed on the counter as an x1, x2, x3, etc. next to a skull and crossbones. This proximity sensor allows the user to know how many enemies are in the blast radius of the grenade. This is can also be used to make the grenade a small mine, and allows the "mine" to be effectively detonated, even if you don't have a good line of sight.
 * The IGL can also be used as an improvised mortar, much like the Halo 2 Brute Shot, this tactic is ineffective at best and is mostly a trick shot to use in Firefight, (you don't get medals for it, but it's still a lot of fun to try!)
 * If the "bottomless clip" setting is activated, the M392 will function identically (gameplay-wise) to the MG460 MGL found on Falcons.
 * It is possible to launch a grenade into a lift and detonate it when it reaches the top. This can foil the would be camper looking for assassination medals.

List of appearances

 * Halo: Reach