They carried only 250kg in the attack on Hermes according to the 'kodochosho' of the 5 carriers, and I also don't know of any case of them being used v US carriers, by divebombers, at least in 1942. But they were used against other targets fairly regularly. For example, the 2nd (later 582nd) Air Group's Type 99's in missions in New Guinea in 1942, usually v Allied airfields, usually dropped either250 plus pair of 60's, or just the pair of 60's, according to their mission reports.
The 60kg was used against Allied ships, but usually by Land Attack Planes or Carrier Attack Planes bombing horizontally, when lacking torpedoes, and/or loaded out for possible land targets, then diverted to ship targets; or by floatplanes. For example in the Dutch East Indies USS Langley and Marblehead suffered apparent 60kg hits in different attacks by Land Attack Planes: the attackers were dropping a mix of 60 and 250kg. Type 97 Carrier Attack Planes (Kates) also went after ships with 60kg bombs at times, for example Ryujo's attack on seaplane tender William B. Preston at Davao Gulf PI first day of the war.
Joe
Thx. This syncs with what i'd dug up vis-a-vis land vs sea targets and the D3A. Taking the additional time to arm carrier bombers with the bomblets vs. naval targets didn't seem sensible. (Despite some quoting CV magazine stockpiles) However land targets made more sense for the weapon and justified their presence in magazines.