If Japan's 25 mm antiaircraft gun worked like the Oerlikon

How would the Pacific War change if Japan's 25 mm antiaircraft weapon matched the American 20 mm Oerlikon in effectiveness?

The strategic result would probably remain the same, but American aircrew losses would rise and rebuilding carrier air groups could lengthen intervals between operations.

A more effective Japanese light antiaircraft gun would kill more pilots and damage the tempo of American carrier operations. That improvement would not reverse the war, because the United States could still replace aircraft and rebuild air groups. The change matters chiefly in casualties and campaign timing rather than final outcome.