This is mostly an issue on lower levels. At steel path, you can charge shotgun incarnons in 1 - 3 shots. But at low levels? Because how seemingly 1 pellet is what kills an enemy it only counts that towards the incarnon meter from what I imagine is how it works. So because multiple pellets aren't hitting at the same time because only the first ones counting while the rest probably don't because you one shot everything, this severely hampers incarnon shotguns at "lower" levels vs high levels.