It is unclear to me how many pellets you have, but from testing with a 2 shot combat shotgun with max mods compared to a 25 bleed combat shotgun with same mods, the bleed is way better. Shotguns effects (like bleed, explosive etc) is per pellet, not per shot. for automatic weapons it's a bit trickier, if the affix is adding more damage than the shot itself, it's better with burn&bleed etc, if not, 2 shot as well. Two shot is by far the best for single shot weapons, with the exception of shotguns.
