There are 5 types of Heavy Weapons in the main game, and a 6th available on Zaeed's loyalty mission.
M-100 Grenade Launcher (Found during the opening mission)
ML-77 Missile Launcher (Research)
M-622 Avalanche (Research)
Collector Particle Beam (Found on Horizon)
M-920 Cain (Research)
M-451 Firestorm (Found during Zaeed's Loyalty Mission)
Arc Projector (Provided with the Cerberus Pack)
M-490 Blackstorm (Available through Terminus Weapons and Armor DLC)
