Hitting an enemy gives them 1-4 stacks of 2.5% Brittleness. Debuff lasts for 5 seconds and can have a maximum of 16 stacks.
5-8% toughness on Chained Hit.
2-5 bullets loaded from Reserve on Critical Hit.
1-4% Toughness for every 10% of magazine spent during continuous fire. Stacks 5 times.