Zero Ammo Cost

All weapons consume zero ammo in Main Story and Separate Ways. (Yes, this includes infinite grenades)

Note:
The UI will not display the infinity symbol.
You'll know the mod is active when the ammo count remains unchanged.
You can find this mod under the Misc category
This mod pretty much eliminates the need to pick up ammo or reload.
You'll have inifinite throwables e.g. grenades, chicken eggs, etc.

If mod isn't working:
Update to latest version of the mod manager.
Uninstall all mods via the mod manager.
Click on "re-read game archives" in the mod manager. 
If the previous step doesn't work, try deleting the mod and redownloading the files.