In August 1994, at the third session of the group of governmental experts to prepare the 1995 Review Conference of the 1980 United Nations Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which May be Deemed to be Excessively Injurious or to Have Indiscriminate Effects, Switzerland introduced a proposal for a new protocol to the Convention. The Swiss draft Protocol on Small-Calibre Weapon Systems would prohibit the use of small-calibre arms and ammunition which, at ranges of 25 metres or more, transfer more than 20 Joules of energy per centimetre to the human tissues during the first 15 centimetres of passage in the body.
1 This article was also published in the University of Essex Papers in the Theory and Practice of Human Rights.
2 Rapid energy transfer results in the violent formation of a “temporary cavity” in elastic tissues such as muscle. The temporary cavity expands and contracts very quickly several times before collapsing around the “permanent cavity” or wound track left behind as a record of the passage of the missile. According to the findings of an extensive wound ballistics research project conducted at Princeton University during World War II, “study and measurement of a large number of temporary cavities show that the total volume of the cavity is proportional to the energy delivered by the missile”. As the Princeton study revealed, the stretching and displacement of tissues during the formation and contracting of the temporary cavity can result in serious damage within a large region around the path of the missile. Tissues are torn and pulped, capillaries are ruptured, nerves may lose their ability to conduct impulses, soft organs may be damaged, gas-filled pockets in the intestines can rupture, and bones that have not suffered a direct hit may be broken. (Harvey, E. Newton, McMillen, Howard, Butler, Elmer G. and Puckett, William O., “Mechanism of Wounding”, pp. 144, 175, 197–198, 201–211, in Beyer, James C., ed., Wound Ballistics, US Department of the Army, Washington, 1962, pp. 143–235.) It follows that the larger the temporary cavity, the greater the extent of damage and the greater the risk of damaging a vital organ which is not directly in the path of the missile.
Energy transfer (also referred to as energy deposit) has long been recognized as a crucial element in missile wounding. It was, for example, the main factor used in a 1969 US Army Laboratory study of the wounding capacity of M16 rifle ammunition. The study noted without disagreement that “previous investigators have asserted the inherent logic in the assumption that the level of incapacitation which would be caused in a soldier by a missile is proportional to the amount of energy deposited in a target by the missile”. The previous investigators referred to had studied the wounding capacity of fragments, rifle bullets, and flechettes. (Sturdivan, Larry M., Bruchey, William J. Jr and Wyman, David K., “Terminal Behavior of the 5.56 mm M193 Ball Bullet in Soft Targets“, US Army Ballistic Research Laboratories report No. 1447, 08 1969, p. 24.)
3 A US Army weapons engineer wrote in 1967: “Bullets can be designed to deform in a dense medium, such as flesh; Geneva Convention [sic] and other rules, however, prohibit their use. To conform to such rules and still maintain a typical bullet shape (ignoring dart-like configurations), the optimum wound ballistics design is often considered to be one that imparts maximum kinetic energy to the flesh by means of high drag”. The logic of this statement is that a bullet producing exactly the same effect as a dumdum bullet — maximum energy transfer — will “conform” to the laws of war as long as the bullet itself does not mushroom. (Roecker, Eugene T., “The Lethality of a Bullet as a Function of its Geometry”, US Army Ballistic Research Laboratories report No. 1378, 10 1967, p. 13.)
4 Dimond, Francis C. Jr and Rich, Norman M., “M-16 Rifle Wounds in Vietnam”, Journal of Trauma, Vol. 7, No. 3, 1967, pp. 620–624.
5 Stockholm International Peace Research Institute, Anti-personnel Weapons, Taylor & Francis, London, 1978, pp. 98–104.
6 Document CDDH/DT/2, submitted by Egypt, Mexico, Norway, Sweden, Switzerland and Yugoslavia, later joined by Sudan, as quoted in Blix, Hans, “Current Efforts to Prohibit the Use of Certain Conventional Weapons”, Instant Research on Peace and Violence, Tampere, Vol. 4, No. 1, 1974, pp. 21–30.
7 A detailed account of the US World War II wound ballistics research programme may be found in Harvey, et al. , op. cit.
8 International Committee of the Red Cross (ICRC), Weapons that May Cause Unnecessary Suffering or Have Indiscriminate Effects; Report of the Work of Experts, ICRC, Geneva, 1973, Table III. 1, p. 34.
9 Dimond, and Rich, , op. cit., p. 624.
10 ICRC, 1973, op. cit., paragraph 112, p. 38. The group of experts was convened by the ICRC at the request of 19 States represented at the second session of the ICRC Conference of Government Experts on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts. At both the first (1971) and second sessions of the Conference of Government Experts, Sweden and other countries had called for the elaboration of explicit draft prohibitions of specific categories of conventional weapons. (Blix, , op. cit.)
11 International Committee of the Red Cross, Conference of Government Experts on the Use of Certain Conventional Weapons (Lucerne, 24.9–18.10.1974); Report, ICRC, Geneva, 1975, paragraph 129, p. 40.
12 Ibid., paragraph 151, p. 46.
13 Ibid., paragraph 154, p. 47.
14 Document CDDH/IV/201, part IV, reproduced in Official Records of the Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts; Geneva (1974–1977), Berne, Federal Political Department of Switzerland, 1978, Vol. 16, p. 602. Document CDDH/IV/201, a working paper, was submitted by Algeria, Austria, Egypt, Lebanon, Mali, Mauritania, Mexico, Norway, Sudan, Sweden, Switzerland, Venezuela and Yugoslavia, later joined by Afghanistan, Colombia and Kuwait.
15 Document CDDH/IV/204, reproduced in ibid., p. 607.
16 The resolution is reproduced in Sandoz, Yves, “Prohibitions or Restrictions on the Use of Certain Conventional Weapons”, International Review of the Red Cross, No. 220, 01–02 1981, p. 33.
17 International Committee of the Red Cross, Conference of Government Experts on the Use of Certain Conventional Weapons (Second Session — Lugano, 28.1–26.2.1976); Report. ICRC, Geneva, 1976, pp. 61–69, 116–119.
18 Sellier, Karl G. and Kneubuehl, Beat P., Wound Ballistics and the Scientific Background, Elsevier, Amsterdam, 1994.
19 The angle of incidence of a projectile (also known as yaw) is the angle between the axis of the projectile at any moment and the tangent of the trajectory traced by the centre of gravity of the projectile.
20 A full-metal-jacketed bullet striking the body at less than about 600 metres per second remains intact despite tumbling, but at impact velocities above 600 metres per second it deforms as a result of stresses during tumbling. The bullet is squeezed, mainly at the base; bits of lead are squeezed out of the base, forming separate fragments, and the bullet is flattened. When the impact velocity is increased to a certain threshold, the bullet separates into two parts of approximately equal size, in addition to the fragments from the core. At still higher impact velocities, more fragments are produced. (Sellier, and Kneubuehl, , op. cit., pp. 174–177.) The wounding effects of bullet deformation and fragmentation have been studied by, among others, Martin L. Fackler of the Wound Ballistics Laboratory at the US Army's Letterman Army Institute of Research; see Fackler, , “Physics of Missile Injuries”, in McSwain, N. E. Jr., and Kerstein, M. D., Evaluation and Management of Trauma, Appleton-Century-Crofts, Norwalk, Connecticut, 1987, pp. 25–41.
21 Over the past century, students of wound ballistics have used firings into dense media such as clay, water, soap, or gelatin as approximations of what happens when a missile penetrates the body. Because these materials have uniform physical properties throughout and can be cheaply prepared in uniform lots, an experimenter can afford to conduct a series of trial shots, varying such factors as the missile shape, size, or velocity. Materials such as gelatin and soap are good “flesh simulants” in ballistic tests because their density is close to that of the soft human tissues, which — like them — are made mostly of water.
22 Kent, R. H., “The Theory of the Motion of a Bullet about its Center of Gravity in Dense Media, with Applications to Bullet Design”, US Army Ballistic Research Laboratories report No. X-65, 14 01 1930.
23 Roecker, , op. cit.
24 Op. cit., p. 138.
25 Interior ballistics (the motion of a projectile inside a gun), exterior ballistics (its motion through the air) and terminal ballistics (its motion on hitting a target) are the three branches of the science of ballistics. Wound ballistics is a subfield of terminal ballistics.
26 The M16 twist had earlier been increased from one turn in 14 inches so that the bullet would be stable when fired in Arctic conditions (Jane's Infantry Weapons 1975, Jane's Yearbooks, London, 1974, p. 327).
27 de Veth, C., “Development of the New Second NATO Calibre: The 5.56' with the SS 109 Projectile”, in Seeman, T., ed., Wound Ballistics; Fourth International Symposium, Acta Chirurgica Scandinavica, Stockholm, Supplementum 508, 1982, pp. 129–134.
28 A flechette is a small, nail-like object with several fins at the blunt end. In the early 1960s the US Army embarked on a programme to develop a flechette-firing rifle, the “Special Purpose Individual Weapon”. In 1966, engineers working at AAI Corporation, one of the companies involved in the project, filed applications for patents on a “concavecompound finned projectile” and a “multiple hardness pointed finned projectile” (granted as US patent numbers 3,861,314 and 3,851,590 respectively). The purpose of both of these constructions was to make the nose deform on impact, causing the flechette to tumble. (“It will be readily apparent that increased effectiveness is obtained with this projectile in a soft, dense type target, such as an animal, due to the tumbling and enlarged effective projected peripheral area of the projectile in the tumbling curled configuration … as compared to the small piercing configuration of the projectile if it should pass into or through the target in a straight linear fashion”, the inventor wrote in the second patent application cited above. The first application contained similar language.)
Another design, tested for wounding effects at the US Army Ballistic Research Laboratories, was for a bimetallic flechette; the two metals would have separated on impact, greatly increasing the area pushing against the flesh. The deformation of the first two flechettes is very close to the “expanding” or “flattening” of dumdum bullets, in the terminology of the Hague Declaration, and the break-up of the bimetallic flechette would be prohibited under the Hague Declaration if the Declaration were applied to flechettes. (As Louise Doswald-Beck and Gerald Cauderay have pointed out, “the French authentic text [of the Declaration] refers to ‘balles qui s'épanouissent’, which means bullets which open up, and therefore includes fragmentation”; Doswald-Beck, Louise and Cauderay, Gerald, “The Development of New Anti-personnel Weapons”, International Review of the Red Cross, No. 279, 11–12 1990, pp. 565–577, at p. 568.)
29 Cf. Sellier, and Kneubuehl, , op. cit., p. 313.
30 The use of energy deposit as a criterion for wounding effect is an improvement over the Swedish working paper on “Possible Elements of a Protocol on Small-Calibre Projectiles”, introduced at the CDDH in 1976 (document No. CDDH/IV/214, cited above). The Swedish paper proposed banning the use of small-calibre projectiles which, among other things, tumble rapidly in the human body; with reference to tumbling, it specified that the average yaw angle (angle of incidence) of the projectile must not exceed an agreed number of degrees during the first 14 centimetres of penetration. The Swedish paper and the Swiss draft Protocol describe the same phenomenon, but the measurement of average yaw angle as required under the Swedish text would have necessitated the use of expensive equipment for high-speed photography in gelatin or high-speed X-ray photography in other media, or for average yaw angles to be derived from other measurements by an agreed formula.
31 For a discussion of the choice of flesh simulants, animals, and other materials used in ballistic tests, see Seliier, and Kneubuehl, , op. cit., pp. 188–214.
32 According to Kneubuehl (personal communication), the onset of the temporary cavity corresponds to an angle of incidence of about 20 degrees.
33 The Swiss draft applies only to ranges of 25 metres or more. The reason for excluding shorter ranges is that bullets at these ranges are subject to a yawing motion. As Seliier and Kneubuehl have noted (op. cit., p. 109), gas flows produced by the air column ejected from the gun barrel or by powder gases flowing around and in front of the projectile can be observed at the muzzle of the gun before the bullet has left the barrel. During the first few centimetres of its flight, these gases exert a lateral force on the bullet, setting up a yawing motion (a periodic deviation of the attitude of the projectile from a nose-on orientation). During the first 10 to 20 metres of its flight, the angle of incidence of the bullet varies between 0.5 degrees and 3 degrees, reaching the maximum every 1.5 to 3 metres. As the propensity of a bullet to tumble in the body is greatly affected by the angle of incidence at the moment of impact, it is quite possible that one bullet, striking a person at close range with an angle of incidence of, say, 3 degrees, will tumble soon after penetrating the body, causing a severe wound, while an identical bullet, fired under the same conditions, will strike with a minimal angle of incidence and start tumbling much later.
After 10 to 20 metres' flight, the effect of the spinning motion of the bullet (known as angular momentum) overcomes the yawing and the angle of incidence declines. It is at these longer ranges that the difference in wounding effect of different small-calibre weapon systems becomes evident.
34 Another possibly significant factor in the wounding process, not covered in the Swiss text, is the effect of a small-calibre projectile hitting bone. At the ICRC expert meeting in 1994, Kneubuehl stated:
“When a rifle bullet hits a bone shortly after the impact, it penetrates the bone with only a small loss of velocity and energy. Measurements showed that at an impact velocity of 800 metres per second the velocity decreases by only 30 metres per second (energy loss ca. 220 Joules) penetrating a femur. The resulting impulse is too low for deforming or breaking the projectile. On the other hand the penetration of the bone disturbs the stability and after [penetrating] the bone the bullet turns earlier to the sidewise position. So it is possible that a bullet which would not break in soft tissue can fragment after hitting a bone because of the earlier destabilisation. Bullets that hit bones with low velocities have not yet been examined”.
The effects of missile shots into bone have been studied much less than effects in soft tissues. It is possible that future research may reveal differences among small-calibre weapon systems as to the severity of wounds produced as a result of projectile deformation or tumbling when hitting bone. If it turns out that these differences are significant and do not coincide with the differences in severity of injury in soft tissues already covered under the protocol, the protocol could be modified accordingly.
35 As Karl G. Sellier stated at the third International Symposium on Wound Ballistics in 1978, “An essential demand must be to make the narrow channel as large as possible, that is to utilize bullets with the largest possible longitudinal moment of inertia. By means of an elongation of the narrow channel one can, in practice, attain that no vital organs lie in the range of the extremely large wound cavity, which is caused by the transverse position of the bullet”. (Sellier, Karl G., “Effectiveness of Small Calibre Ammunition”, in Seeman, T., ed., Proceedings of the Symposium on Wound Ballistics, Acta Chirurgica Scandinavica, Stockholm, supplementum 489, 1979, pp. 13–26, at p. 24). According to Kneubuehl's figures (which, like those quoted earlier, are based on only a limited number of test firings), the 7.62 mm NATO bullet travels 19 centimetres before starting to deposit energy rapidy, and by 22 centimetres it has deposited 600 Joules of energy. Thus the SS 109 bullet, while an improvement over the M16 bullet, is still more likely to cause a severe injury than the larger-calibre NATO round.
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