Fated Circle should be attained at an earlier level. Having no AOE option for the endless shells of leveling up to 72 feels pretty bad. Trade it with Heart of Light IMO.

"Brutal Shell"'s shield trait should instead be traited to occur whenever you expend Ammo / complete the ammo combo. Have it be 50% shield for a much beefier hit while also giving the Gunbreaker a defensive angle for cartridge expenditures.

Blasting zone having a decaying aoe factor would be icing on cake.

Otherwise, feelsgood.jpeg.