What weapon mods can be found, and what are their effects

What are the weapon mods that can be attached to your soldiers weapons, and what do they all do?

There are 7 possible mods, and all weapon mods have 3 levels - basic (no prefix), advanced, and superior. Bonuses listed as x/y/z correspond to those 3 levels.

• Stock - 1/2/3 Guaranteed damage on a miss.
• Auto-Loader - 1/2/3 Free Reloads per mission. (Reloading doesn't cost an action)
• Extended Magazine - 1/2/3 extra ammunition before reloading.
• Repeater - 5/10/15 percent chance to instantly kill an enemy, regardless of remaining health. ("Executed" text will pop up when this triggers)
• Scope - 5/10/15 Aim bonus when using the upgraded weapon. 10/15/20 Aim bonus when using the upgraded weapon against targets not in cover. (Does not apply to secondaries)
• Laser Sight - 5/10/15 Crit chance when using the upgraded weapon. (Does not apply to secondaries)
• Hair trigger - 5/10/15 percent chance for each shot to not use an action.