A shuttle weapon would specifically be designed for use outside a sealed environment or to breach one. So I have no problem with it being slug or explosive. But I like the idea of a plasma weapon for breaching, also useful outside atmosphere for close work. But from existing cannon you would expect it to be a small primary beam weapon.
I could see marines carrying plasma as heavy weapons support.
I think for our typical work the carbine fills the role of heavier support weapon.
So I am seing for security and personal defense
– Beam pistol
– Unarmed combat
– Single eye HUD/sensor/Monocle plus jaw-mounted comms/calc/sensor (especially because these exist in the avatar creation program)
Damage control
– Padded-Mesh armour for impact and energy absorption (various types in avatar creator)
– Helmet
– Ceraknife
– Cutter/welder (heavy beam pistol)
Crowd control (MPs?/Security)
– Truncheon (of some kind)
– Tasers either wire or via ionization trail from a laser
– Sonic stunner?
– Sonic/strobe grenade
– Irritant/tranquilizer spray/gas
– Shield (physical)
Combat work
– Shortsword (Kukri/gladius/wakizashi)
– Beam-carbine (avatar creator “L5-Hyper-rifle” see pic of Nhaima)
– Breaching charges
– Headgear
Support weapons (vehicle or armour-mounted)
– Marine combat armour
– Vibroknife/monofilament
– Energy shield
– Plasma cannon
– Grenade launcher/mortar
– Incendiaries
– Light primary beam emitter
– Slugthrowers chemical or gauss (plain/HE/AP/HEAP/tracer/flechette/tranq)
Tactically don’t forget beams are line of sight and they give away the location of the shooter. Not very important aboard ship but…