Mass Effect 3 Priority: Mars Weapons
M-92 Mantis Sniper Rifle: Turn right just after dropping from the first ledge. It’s next to the corpse.
M-4 Shuriken SMG: Inside the base in the security control room. Look on the ground near one of the corpses.
M-15 Vindicator Assault Rifle: From where you find the Shotgun Shredder mod, check the other side of the room, left of the exit door.
Mass Effect 3 Priority: Palaven Weapons
M-97 Viper Sniper Rifle: Among the crates in the middle of the turian camp.
M-27 Scimitar Shotgun: Next to the barrier on the left as you’re leaving the turian camp.
Mass Effect 3 Grissom Academy Weapons
M-22 Eviscerator Shotgun: Before reaching Orion Hall, you’ll find yourself in a large classroom with a shield generator inside. Fight the enemies that show up, then go through the door next to the shield generator. Turn left to find the M-22 Eviscerator on the bench.
M-96 Mattock Assault Rifle: From the Eviscerator, go back into the classroom and take the door directly across from the one you just used (this is the path to your objective anyway). On the other side of that door you’ll see two orange benches back to back. The Mattock is on the right bench.
Mass Effect 3 Priority: Sur'Kesh Weapons
M-13 Raptor Sniper Rifle: Get up to the second level and bypass the locked door. Go through, but instead of turning left to fight the enemies, continue forward and around the corner to your right to find this weapon on a bench.
Scorpion Heavy Pistol: When you reach the power terminal, look on the ground nearby for this weapon.
Mass Effect 3 Attican Traverse: Krogan Team Weapons
M-300 Claymore Shotgun: As soon as the mission begins, enter the capsule and grab this shotgun from the cot inside.
Mass Effect 3 Tuchanka: Extract Turian Survivors Weapons
M-9 Tempest SMG: Just after leaping over a gap you’ll be in front of a downed escape pod. The SMG is on the ground next to two dead turians.
Phaeston Assault Rifle: Not long after your first fight with the harvester, you’ll come across a dead turian. He’s hard to miss, and the Phaeston lies next to him.
Mass Effect 3 Tuchanka: Bomb Weapons
M-29 Incisor Sniper Rifle: After the intense opening fight, you’ll head up a narrow slope at the far end of the battlefield. This weapon is against the left wall of that sloping corridor.
Mass Effect 3 Priority: Tuchanka Weapons
Graal Spike Thrower Shotgun: From where you found the Death Mask, turn around and find this shotgun next to a krogan who’s leaning against the railing.
M-5 Phalanx Heavy Pistol: Once your objective becomes reaching the hammers and your marker starts pointing you to the shroud, you’ll have to clear an open area of enemies then climb up a set of stairs that takes a 90 degree turn to the left. This gun is on the ground at the top of the stairs. It’s hard to miss.
Mass Effect 3 Priority: The Citadel Weapons
M-76 Revenant Assault Rifle: To the left of the screen under which you found the recon hood is a door leading to the bathroom. Inside the bathroom, next to the sink, is this weapon.
M-358 Talon Heavy Pistol: In the room to the right of the malfunctioning door, there’s a console you can use that’s labeled ‘door control.’ Activate it, then go back to the locked office on the other side of the room. Inside that office is the Talon.
M-25 Hornet SMG: On the ground in front of the malfunctioning door.
Mass Effect 3 Arrae: Ex-Cerberus Scientists Weapons
M-6 Carnifex Heavy Pistol: Soon after meeting up with Jacob and the scientists, you’ll have to climb a ladder on your way to the roof. At the top of the ladder, look for this heavy pistol along the left wall.
Mass Effect 3 Lesuss: Investigate Asari Colony Weapons
Disciple Shotgun: You’ll eventually meet one of the Ardat-Yakshi and have a short conversation. In the next room, take out the cannibals, then look for a smaller office to the right. Check the ground inside for this weapon.
Mass Effect 3 Priority: Geth Dreadnought Weapons
Arc Pistol: When Tali joins you aboard the dreadnought, she’ll essentially give this weapon to you during the cutscene. Just make sure to grab it from the console. Don’t miss out on this one!
Geth Pulse Rifle: In the room after the one in which you found the Archon Visor. Again, look to your right to find this weapon on a crate.
Mass Effect 3 Rannoch: Admiral Koris Weapons
Javelin Sniper Rifle: This weapon lies on the ground just beyond where you found the first dead quarian. Be careful: there is a mine right next to it.
Mass Effect 3 Priority: Rannoch Weapons
Geth Plasma Shotgun: You can find this weapon on your way to the shield override, just before going back inside the structure.
Mass Effect 3 Priority: Thessia Weapons
M-98 Widow Sniper Rifle: At the feet of the Asari sniper team.
Mass Effect 3 Priority: Horizon Weapons
M-12 Locust SMG: On one of the desks in Lab 01. You’ll enter this area just after the cutscene in which Shepard has to fix a console.
M-99 Saber Assault Rifle: In the room where you fight three brutes and a banshee, investigate this holographic control panel. Press B/circle to manually override the pods. Now go back to the pod inside which this weapon rests. You can now retract the glass and grab the rifle.
Mass Effect 3 Priority: Cerberus Headquarters Weapons
M-37 Falcon Assault Rifle: After you launch the fighter into the hangar doors, look on the ground near the site of destruction for this weapon.
Congratulations – you've found all of the Mass Effect 3 weapons!
