What if the US Navy adopted a pom-pom instead of the 1.1-inch Chicago Piano in the 1930s?
Short answerThe pom-pom is judged a better early weapon, while its place in American doctrine and the subsequent adoption of Bofors remain open questions.
NotesThe pom-pom was already about twenty years old in the scenario's early-1930s setting, so the premise becomes American licence production of an existing weapon. It is judged a better weapon than the 1.1-inch Chicago Piano for producing a dense volume of anti-aircraft fire. How it develops in American service would depend on its place in naval doctrine. Widespread adoption could also alter the later reputation and distribution of Bofors guns.