Honestly there is no real reason to run heirlooms over Jotun in its current state besides the anti champion capability. All it needs in my opinion is a larger ammo capacity, maybe double its current 20 ammo to 40. Otherwise it shouldn't generate heat while charging it or being ads. Also the charge should be decoupled from ads and instead require holding down the fire button. Otherwise the exotic feels like its suffering from an identity crisis since Jotun does the same thing just with a smaller blast radius. If bungie leans into the charge fantasy, it should be dealing rocket level of damage at max charge.