The Carbine in Halo 5: Guardians is more accurate (especially at longer ranges) and faster than the Type-51 model from earlier games, but has slightly more reticle bloom and otherwise operates exactly the same.
In comparison to the DMR and LightRifle, the Carbine has a faster rate of fire than both weapons and more range than the LightRifle but deals less damage.
Like with the T-51, the T-57B Carbine leaves behind visible green trails that give away the shooter's position. In dark or chaotic areas, this will help you determine where your enemies are.
Carbines can be obtained in any mission featuring Covenant enemies. They are commonly found in the hands of Jackal Snipers and Elites.
If you encounter Jackals that are on patrol or have their back turned to you, simply aim for the head and pull the trigger, resulting in a one-hit kill. However, if in the middle of a firefight, instead run up towards the Jackal, melee it or shoot the exposed hand or feet which should make it flinch and take away its shield for an instant, and kill it with a headshot. Carbine rounds inflict damage on the Jackal's personal shield, dropping the shield within 4 - 10 shots depending on the difficulty and providing you with a clear shot at their head. However, unlike with the Storm Rifle, the damage done is not enough to actually collapse the shield with a reasonable amount of shots and is rather wasteful of ammo.
Warzone and Arena feature two additional variants of the Carbine, both with an increased maximum reserve round count of 100:
Rain of Oblivion: an improved variant with fully automatic fire with a trade-off of a 36% lower smart scope red reticle range. This variant is effective if the player wants to keep their current weapons but does not want to switch out their existing precision weapon for a fully automatic one, as the Rain of Oblivion functions as a fully automatic precision weapon.