Make the Mastiff unique to other shotguns with a little buff
Every ammo type has that one weapon that is a little different from others, [aside from light but I'm still thinking of something for that] snipers have the charge rifle, energy has the l-star, heavy now has the rampage, but what about shotguns and you could say the peacekeeper has the precision choke but every other weapon I listed is greatly different from the rest of their ammo type. Since the mastiff fires incendiary rounds it should deal small amounts of damage over time like the person you hit is slightly burning, and a buff like that could bring it back to par with the other shotguns that outmatch it.
