to clarify longer bullets help with soft cover not tracers (tracers just have longer bullets).  the navy knew this in the 1800's which is why they switched to the 6mm lee when everybody else used the 45-70  > "the round was intended to perforate the hulls of small enemy craft such as patrol and torpedo boats, and could penetrate 13 in (330 mm) of softwood at 700 yd"
United States