I didn’t know that Overwatch’s engine even tracked damage that isn’t whole numbers.
Can it even count 0.6 damage per pellet individually or does it count all the impacts in a single frame at once and then add up the fractions?
If you hit somebody with a number of pellets that isn’t divisible by 5, you are going to get some fractional damage. What happens then? Does it round up or down?

Maybe this is secretly a placebo buff to see how many people complain for no reason because it is actually still doing only 6 damage per pellet.