Assault Squad
Space Marine chapters sometimes need fast-moving, versatile troops that can be easily inserted onto the battlefield and made to quickly close with the enemy. If 8-foot power-armoured posthumans weren't good enough, now they come with jetpacks.
Assault Squads are one of the Tactical Squad's cousins. They are of a similar size (5-10), but shun bolters and other long-range weapons in favour of jump packs, chainswords, power weapons, and bolt pistols. Assault Squads are usually deployed from Thunderhawk Gunships, slowing their drop with their jetpacks, but it is not unheard of for squads to make use of Drop Pods or even Rhinos. Once on the battlefield they aim to enter close-to-mid-range combat with the enemy, harassing their front lines and using the jump packs to quickly switch targets.
All Codex-compliant space marine chapters move new recruits to Assault Squads after their duty in Devastator squads, using it as a second and final level of training before the recruit's full induction as a tactical marine within the chapter.
The Blood Angels use Assault Squads as part of their main forces, as opposed to a supporting force. In a departure from the Codex, Blood Angels Scouts will be placed in Assault Squads, to allow them a chance to use their natural instinctive for close combat without ruining a battle plan by risking a fall to the Red Thirst (Devastators are Veterans who have shown better control over resisting the Thirst). Every Blood Angel tactical marine maintains his jump pack and close-combat training from his duty in the Assault Squads, allowing the chapter to form massed Deep Strikes of Assault Marines. When not acting as Terminators, the Blood Angels First Company will function as Vanguard Veterans.
Among the Space Wolves, the role of Assault Marine is given to the Blood Claws, neophyte Wolves who are still coming to grips with the inner Wolf and expending their fury by charging the enemy. However, they do not use Jump Packs, which are instead given to Skyclaws, who are considered the trouble makers in a Chapter of Space Vikings who don't like flying: "If the Allfather wanted us to fly, he would have given us wings."