This thing is unreliable for MMM + MMM BoS Spawns. It seems that every 4-6 shots the blasted thing jams and forces a reload. Is it meant to be like this by design as a coutermeasure for being so powerful? I've noticed the Mutant Overlords seem to have the same problem or else they are pausing because I'm staggering. With setting fDamageWeapons == 4.8, Overlords are everywhere in the DC area. A jamming Tri-Beam doesn't cut it for a group of powerful hostiles.
Havelock1000 is correct. The tri beam fires 3 projectiles and has a clip size of 24 so it reloads after every 8 shots. It's an excellent weapon when you know how to use it.