M3 Predator: First weapon acquired during the Prologue.

Scorpion: In the "Priority: Sur'Kesh" mission, it is found on the floor where Mordin requires you to reactivate the elevator power source. After reactivating the power, find the weapon before turning on the elevator.

M-5 Phalanx: In the "Priority: Tuchanka" mission, it is found on the ground, up the steps leading to the long stretch where the Reaper starts firing its laser at your team.

M-358 Talon: In the "Priority: Citadel" mission, while in C-Sec HQ, you will enter a dark hallway with four offices. One of the first offices is locked. Proceed down the only path forward to find a computer console that will open the office door. Go back and open the door to find the pistol near some other weapons.

M-6 Carnifex: In the "Arrae: Ex-Cerberus Scientists" side-mission, it is found on a pipe in the red-bathed maintenance hallway before taking the ladder up.

Arc Pistol: In the "Priority: Geth Dreadnought" mission, it will be given to Shepard by Tali.

M-77 Paladin: It can be purchased from Spectre Requisitions terminal in the Spectre Office at the Citadel for 200,000 credits.