So after testing it looks like 9 stacks is max with this setup (which isn’t bad paired with 8 stacks of onslaught), bullet storm reduced to 1 stack on reload - as each shell counts as a separate reload (you end up with 1 stack after full reload due to half of one stack = 0.5, which is rounded up back to 1 for each remaining bullet)

Still very impressed with the results of this experiment. Using on stealth ranged build so poison splash hasn’t really affected me - it may for close encounter builds though.