The Heckler & Koch MP5, simply known as the Submachine Gun or SMG, is a weapon featured in Half-Life and its expansions. The primary weapon used by the HECU, it is an automatic weapon with a high rate of fire. It is also equipped with the 'Shorty' version of the M203 grenade launcher that boosts its effectiveness.
The attached grenade launcher fires powerful explosives that will automatically explode when hitting the ground. It does not need to be reloaded, so the player can fire as many grenades as they want until they run out of grenades.
Both the MP5 and the Glock 17 use 9×19mm Parabellum and share the same ammunition reserve, making the MP5 and the Glock 17 very easy to find ammunition for.
This weapon is first obtained at the start of the Half-Life chapter "We've Got Hostiles". It can be found next to a dead HECU soldier in the first room that has sentry guns. After that, it can be found in areas controlled by the HECU and picked up from dead HECU soldiers.
When a player picks up an MP5 for the first time, it will have 25 rounds; the player must reload the gun to get the total 50 rounds in the magazine. Every additional MP5 that the player picks up (e.g. from killed enemies) also grants them only 25 rounds in reserve, but picking up individual magazines actually grants them 50 additional rounds.
The MP5's accuracy is too bad for anything that was too far away, requiring burst-fire attacks to be used more effectively. The recoil was increased in Half-Life: Source, effectively preventing it from tackling long-range targets.
The player should be sure not to use the MP5's bullets against large groups of enemies for the MP5's bullets do only 5 points of damage. Save the bullets and fire the MP5's grenade launcher instead.
Groups of weak enemies, such as Headcrabs or Houndeyes, can easily be killed with the MP5.
The MP5 is effective on small groups of Vortigaunts and HECU Marines. With Vortigaunts, one should remember to move often to avoid being hit by the Vortigaunts electric bolts. With HECU soldiers, one should stay out of their effective range or make use of cover, since they have the same SMGs and slightly better accuracy.
The Alien Controller is easy to kill with the SMG. Since its bullets hit instantly, the player can attack the Controller and avoid its slow-flying plasma balls with ease.
The MP5's accuracy is not increased by crouching except in the source port.
In multiplayer, the MP5 is more accurate, though the opposite was true in early versions of Half-Life.
The grenade launcher should be used to clear out large groups of enemies at once. One grenade can kill up to five HECU soldiers with ease if it lands in the center of the group.
The grenade launcher is also effective against enemies that have a lot of health, such as the Alien Grunt. One grenade can usually kill it in one shot, and one can easily finish it off with a few bullets if it does survive the grenade.
Using the grenade launcher against weak enemies, such as Headcrabs, is obviously effective but is a waste of ammunition (unless it is a group of Headcrabs). Melee attacks or normal bullets from any sidearm are more advised.
The grenade launcher is one of the few weapons that can damage a Gargantua, so one should stock up on its ammo when wanting to kill a Gargantua manually.
If the grenade launcher is used at long range, intelligent enemies can usually run away from it before it explodes. Therefore, getting closer to the intended victims before firing is advised, as it prevents them from running away. However, being too close will affect the player's health, as with all explosive weapons.
Behind the scenes
In the playable Half-Life Alpha, the MP5 is still based on an MP5SD, but HECU Grunts use Colt 727 Rifles. The switch to an MP5 was made early in development, replacing all Grunt rifles to the MP5 to match the player's weapon. that being said, the Half-Life High Definition Packcreated by Gearbox Softwareturned it back into an Colt Model 727 Assault Rifle.
The original MP5 had a different firing sound than the retail one. In addition, it could carry more than 10 grenades.
The retail viewmodel and the early worldmodel is an MP5SD, while the retail worldmodel is a regular MP5.
In the Half-Life High Definition Pack, the 727 still uses the same ammunition reserve as the pistol.
Early textures for the MP5 can be found in the Half-Life SDK files.
The MP5 originally used 30-round magazines (which are far more common in real life). It was changed to 50 in the final game. The model, however, has a 30 round magazine.
The Half-Life: Day One viewmodel is different from the retail model, however this can be only seen through a model viewer. The left arm is bugged and its only polygon is always attached to the magazine, and there's chrome on left arm instead of red stripes.
All NPCs fire the MP5 in bursts of three or four rounds, except when they are rappelling down.
The HUD icon for the MP5 has a missing magazine, making it look vaguely similar to a PP-19 Bizon. The barrel, handguard, front sight, and grenade launcher sight also look similar to that of an M4/M203 Combo.
The grenade launcher has a few flaws, which will completely prevent it from being fired in real life. One, is that launcher has no trigger. Two, the grenade is not seen being reloaded and three, it is always launched with the shell.
While the MP5 is replaced by a Colt 727 Rifle in the high definition packs and PlayStation 2 port for Half-Life, its stats remain unchanged, keeping the 50-round capacity in a 30-round magazine, having the same low damage and accuracy, and even sharing the same 9mm ammunition pool as the MP5 (with the exception of the PS2 port, where it has its own ammunition type).
The damage in Half-Life: Source is increased to 8 per bullet instead of 5 (the same damage inflicted by the Glock 17).
MP5 held by Adrian Shephard in Half-Life: Opposing Force cover art seems to lack the grenade launcher. The model also seems to be consistent with the in-game world model, instead of the MP5SD used for the first-person model.