Talk:Mods 2.0/@comment-8069771-20130420171713/@comment-7700557-20130420175224

Depends on what you mean by "stack". If you put several elemental damage mods on your gun, the extra damage for each is calculated separately on the base damage of the gun multiplied by the regular damage mod if there is any. Elemental effects don't multiply each other; they only depend on base damage. They do take effect all at the same time.

This explanation might be confusing; a more thorough explanation, as well as the proper formula, is in the Damage page.