Almost every heavy weapon is a Tech Lab Prototype, but the flamethrower (not including grenade launcher cause you have to pick it up) is found in Zaeed's loyalty mission you must have the Cerberus Network to get this, it is on the floor after you have entered Vido's base after you are finish talking with the civilian who says they are trapped. Also the Geth Pulse Rifle is found in the same mission you go after Tali, it is found at the end after you fight the Geth Colossus and before you talk to Tali, there is a large Geth dead on the floor through the door and on him is the Pulse Rifle. Next you find the Tempest SMG in the mission you go to find Tali, it located next to a dead Geth Hunter, some Geth Troopers, some Quarian soldiers, and a radio where you communicate to a Quarian captain, I don't remember his name sorry.

The Schimitar Assault Shotgun is found in the mission you go to get Samara, it is found on a desk on the right hand side of the room near a weapons locker, sorry don't remember fight that occurred right before this. The Viper Sniper Rifle can be found all throughout the mission you go to find Thane the Assassin, next to a terminal where Nassana is talking, next to the bridge you take to switch towers, and on a u-turn next to an elevator which brings down a mini-boss. Next the Canifex Hand Cannon is found in the mission you go to find Mordin, when you meet Mordin in his clinic he hands you the Hand Cannon. Garrus) when you meet him there is a bench in the room he is in it is sitting on it. Later on in the game you can get Vindicator Battle Rifle, which is located in the mission you go to get Archangel (a.k.a. After you complete this mission you get the Avenger Assault Rifle, Katana Combat Shotgun, Mantis Sniper Rifle, or the Shurikan SMG in the opening of the next mission. You first find your Predator Heavy Pistol in the locker at the beginning of the game, later in that same mission you come to an lift and beside it is the grenade launcher. Every gun is spread throughout the game and can be found almost very easily, but you could be missing one or two cause you ran over them and didn't look.

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