Both the Shadow of the Seraphs relic (introduced in the 'Tiny Tina's Assault on Dragon Keep' DLC) and the Assassin / Zer0's Tw0 Fang skill have the following effect: "Every time you fire a gun you have a chance to fire twice".
What if I use either with a gun that has a burst fire effect? For example, Sledge's Shotgun - special weapon effect description: "Burst-fires two shots per trigger pull, with a long delay between each burst. Reduced clip size".
How many shots will fire per trigger pull if the Shadow of the Seraphs' or the Tw0 Fang's "fire twice" chance activates with a 'burst fire' weapon?
Also, what if I am playing as Zer0 and have both the Shadow of the Seraphs relic and at least a point in the Tw0 Fang skill? How will their chances of firing a gun twice stack?