Bad Powder I gives Blighter firearms a chance to misfire or blow up. It reduces the danger from gang gunmen.
Bad Powder I is entry 16 of 17 in the Ringleader branch, one of the three branches (Ringleader, Insider and Swindler) on the Rooks' 39-upgrade board. It is bought with money and materials, not skill points: £4,000, 100 Metal, 50 Chemicals. Before Bad Powder I unlocks you need Dull Blades.