Mass Effect 3 Weapon mod location guide 1 – Turian Camp – If you are at General Corinthus and look the direction he is looking take a right. You can buy tons of mods from there! You can buy them from the Normandy if you have the stores unlocked. Mass Effect 3 Weapon mod location guide – The Citadel – Go to the commons presidium and visit all the store kiosks there.