Mass Effect Character Weapon Mods

Weapon Mods are applied to assault rifles, shotguns, sniper rifles, submachine guns, and pistols to augment them. Available mods include high-caliber barrels, scopes, and bayonet attachments, among others. Only two mods can be applied to a weapon at a time, and the same mod cannot be applied twice to a single weapon.
Once a weapon mod is found, it may be applied to any and all of the weapons of the applicable type at a weapon bench. Finding another instance of a mod the player already possesses will upgrade that mod to the next level. Likewise, shops will always carry mods one level above those the player currently has.
Assault Rifle Mods
Shotgun Mods
Sniper Rifle Mods
Submachine Gun Mods
Pistol Mods
Heavy Weapon Mods