Anti-submarine shells and underwater drones

Did navies besides Japan experiment with dedicated anti-submarine shells in the Second World War?

Yes. The Royal Navy and US Navy tried them, and modern concepts may be useful against underwater drones and mines.

The Royal Navy and US Navy are cited as having tried dedicated anti-submarine shells, with a possible Italian experiment also mentioned. Modern versions are presented as more plausible against underwater drones and mines than against a full submarine. Their small explosive charge acts more like a gun-launched depth charge than a submarine-killing weapon. The historical experiments therefore connect directly to present concern about unmanned underwater threats.