You know how a lot of heroes have a secondary fire ability by pressing the left trigger on Xbox and PlayStation and M2 on PC? For McCree, its Fan the Hammer, for Torb, its the spread shot, for Roadhog, its the long range shot, for Moira, it's her damaging grasp, etc.

Reaper should have one of those! Instead of firing the shotguns one after another, he could fire them both at the same time to engage an ambush with a more damaging shot. It'd have a lower fire rate and take two ammo from his clip instead of one. Or, alternatively, you could fire them separately, have one shotgun wired to each trigger? That might not be as good of an idea, but I feel like Blizzard could experiment more with Reaper's kit to see what they can do.