First of all, how it's wrong and bad: the tooltip reads "+30% Extra Ammo Consumed." This is not what it does.
30% EXTRA ammo would be 1.3 ammo per shot, and because it fires twice, a total of 2.6 ammo. But wait... you can't spend a fraction of a bullet. That's silly.
So... what does it...
This button right here:
Doesn't appear to actually do anything. I changed my resolution earlier today so I could keeps tabs on another program while I played some Deadlock, then was unable to restore my 3440x1440 resolution by selecting the "Custom Resolution" option.
Hitting "Apply Settings"...
