Related Rule
New Zealand
Practice Relating to Rule 77. Expanding Bullets
New Zealand’s Military Manual (1992) states that the use of “bullets with a hard envelope which does not entirely cover the core, or is pierced with incisions (Dum Dum bullets)” is prohibited. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 510(c) (land warfare) and 617(c) (air warfare).
The manual notes that the qualification of the use of poison or poisoned weapons as a war crime “is an old-established rule of customary law and applies equally to the use of any forbidden weapon such as expanding (dum-dum) bullets”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1704(2)(a) and footnote 32.
Under New Zealand’s International Crimes and ICC Act (2000), war crimes include the crime defined in Article 8(2)(b)(xix) of the 1998 ICC Statute. 
New Zealand, International Crimes and ICC Act, 2000, Section 11(2).