Related Rule
Australia
Practice Relating to Rule 77. Expanding Bullets
Australia’s Commanders’ Guide (1994) states: “Use of the following types of weapons is prohibited: … (c) bullets with a hard envelope which do not entirely cover the core or are pierced with incisions (dum-dum bullets).” 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 932(c).
The Guide also states: “Hollow point weapons are prohibited because they cause gaping wounds which lead to unnecessary suffering.” 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 309.
The Guide states that these weapons are included in those that are “totally prohibited”. It adds:
These blanket prohibitions, which may be traced to treaty or customary international law are justified on the grounds that the subject weapons are either indiscriminate in their effect or cause unnecessary suffering. 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 304.
The Guide further states: “The following examples constitute grave breaches or serious war crimes likely to warrant institution of criminal proceedings: … using certain unlawful weapons and ammunition such as … expanding rounds.” 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 1305(p).
Australia’s Defence Force Manual (1994) provides:
Weapons such as irregularly shaped bullets, projectiles filled with broken glass, bullets which have been scored, have had their ends filed, have been altered or which have been smeared with any substance likely to exacerbate a trauma injury are prohibited. “Dum dum” bullets (those with a hard envelope that does not entirely cover the core or which have been pierced with incisions or which have had their points filed off) come within this category of weapon. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 405.
The manual further states: “The following examples constitute grave breaches or serious war crimes likely to warrant institution of criminal proceedings: … using certain unlawful weapons and ammunition such as … expanding rounds.” 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 1315(p).
Australia’s LOAC Manual (2006) states:
Weapons such as irregularly shaped bullets, projectiles filled with broken glass, bullets which have been scored, have had their ends filed, have been altered or which have been smeared with any substance likely to exacerbate a trauma injury are prohibited. “Dum dum.” bullets (those with a hard envelope that does not entirely cover the core or which have been pierced with incisions or which have had their points filed off) come within this category of weapon. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 4.7.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Australia’s War Crimes Act (1945) considers “any war crime within the meaning of the instrument of appointment of the Board of Inquiry [set up to investigate war crimes committed by enemy subjects]” as a war crime, including the use of expanding bullets. 
Australia, War Crimes Act, 1945, Section 3.
Australia’s Criminal Code Act (1995), as amended to 2007, states with respect to serious war crimes that are committed in the course of an international armed conflict:
War crimeemploying prohibited bullets
(1) A person (the perpetrator) commits an offence if:
(a) the perpetrator employs certain bullets; and
(b) the bullets are such that their use violates the Hague Declaration because they expand or flatten easily in the human body; and
(c) the perpetrator knows that, or is reckless as to whether, the nature of the bullets is such that their employment will uselessly aggravate suffering or the wounding effect; and
(d) the perpetrator’s conduct takes place in the context of, and is associated with, an international armed conflict.
Penalty: Imprisonment for 25 years.
(2) Strict liability applies to paragraph (1)(b). 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.57, p. 337.
Australia’s ICC (Consequential Amendments) Act (2002) incorporates in the Criminal Code the war crimes defined in the 1998 ICC Statute, including “employing prohibited bullets … [which] expand or flatten easily in the human body” in international armed conflicts. 
Australia, ICC (Consequential Amendments) Act, 2002, Schedule 1, § 268.57.