M57 Pilum

The M57 Pilum Assault Weapon (M57 PAW), also known as the Rocket Launcher, is a shoulder-fired heavy weapon issued to personnel of the UNSC Army, UNSC Marine Corps, and the Spartan branch around October 2558. It performs very similarly to the M41 SPNKR, its predecessor.

Design details
Despite performing much the same as the M41 rocket launcher, the M57 rocket launcher is cheaper and substantially lighter. The M57 rocket launcher is also significantly different in design philosophy, featuring a single, reusable, fixed tube and detachable box magazines rather than dual, rotating, pre-loaded, disposable tubes.

The weapon is fed by a two-round detachable box magazine on the upper left side, forward of the user. The magazine retracts into the weapon when chambering each round, similar to the Type-33 fuel rod gun. A 2× magnification scope folds out from a module on the left side when activated. Its missiles are able to lock onto aircraft if the operator uses smart scope. Standard warheads used by the rocket launcher are 50mm high-explosive multi-purpose, but specialist rounds are also available, including those with thermobaric fillers or dumb AI-driven "brilliant" guidance systems.

Variants

 * Ad Victoriam: An improved M57 that fires three laser-guided missiles in a "V" formation, all equipped with an airburst proximity fuse. The operator can use smart scope in order to guide the missiles with the reticle, and doing so will fire the missiles in a cluster rather than a "V" formation.
 * High Five: This advanced M57 fires five Hydra MLRS mini-missiles that will lock onto both ground and air targets. Unlike the base model and the Ad Victoriam, smart scope is not needed for the High Five's missiles to lock onto targets. Much like the Echidna variant of the Hydra MLRS, the High Five also features a 5× zoom mode that allows the weapon to seek out targets as far as 762 m.

Trivia

 * The M57 bears broad similarities to the anti-air rocket launcher cut from the original Halo: Combat Evolved and the G4H-DuSH cut from Halo 3.
 * The weapon's color palette was changed between the multiplayer beta and final release, going from a more subdued green color to a more vivid green with yellow accents, possibly to increase visual recognition and alert players to its presence.
 * The Pilum is named after the thrown javelin of the ancient Roman army, innovative at its time for its construction: the metal tip was hardened while softer lead connected it to the wooden shaft, which meant it was likely to bend upon impact. If the weapon missed, it would thus be rendered unusable. If it penetrated a shield, this would become weighted down and unwieldy, forcing its user to discard it. If the weapon bent after piercing an enemy combatant, it would be difficult to remove and possibly amplify the wound.

List of appearances

 * Halo 5: Guardians
 * Halo: Shadows of Reach