On Graves, when you auto with RFC at max range, the auto animation will trigger and you will lose a bullet but no auto damage is done.
1. Buy RFC plus a bunch of IEs to get 100% crit chance. Crit indicators are more visible.
2. Auto at max range.
I've only tried this in training, but it could've happened without my knowledge in actual games as well as it's hard to keep track of everything.