Comparative characteristic of clothing and human body simulator gunshot damage after firing with 12-gauge cartridges loaded with expanding and non-expanding slug

Full Text

BACKGROUND

Gunshot bullet damage to clothing and human body simulators has been well-studied concerning rifled [1–3] and limited-damage firearms [4]. Gunshot damage caused by smoothbore weapons, especially using bullets with expanding properties (i.e., disintegrating upon contact with the target), has not been described extensively in modern forensic literature [5–8]. Concurrently, hunting cartridges for 12-gauge smoothbore weapons, including those loaded with expanding bullets, are easily available in the Russian civil weapons market and can be used during crimes. Identification of a wound-causing projectile based on the morphological features of gunshot damage to tissues and clothing is a vital task in forensic medical and criminalistic examination. In the presence of a firearm projectile in the lumen of a dull wound channel, an accurate analysis by the expert may be difficult. However, in the case of a through-and-through wound (especially with structural similarity to several projectiles), identification may be difficult [1].

The study experimentally investigated the characteristics of damage to clothing (coarse calico targets) and the human body imitators by structurally similar expanding and non-expanding lead caliber bullets of 12-gauge (12×70) smoothbore firearm cartridges with a subsequent comparative analysis of their morphological characteristics.

MATERIALS AND METHODS

Study design

An experimental single-center, one-stage, selective, uncontrolled, unblinded study was conducted. Research stages included a study of the medical literature, the creation of experimental targets, shooting at the experimental targets in forensic shooting ranges while filming using high-speed video, a description of the experimental damage to clothing and human body imitators, their comparative analysis, and a discussion of the results.

Criteria of conformity

Experimental gunshot damage to clothing (cotton calico) and human body (parts of a pig carcass) imitators were studied. The selection criteria were the central location of the experimental damage on the targets. Objects with marginal damage were excluded.

Study conditions

Experimental shooting of targets was performed in the indoor shooting ranges of the 111 Main State Center for Forensic and Criminalistic Examinations of the Ministry of Defense of the Russian Federation as well as the Russian Federal Center for Forensic Examination under the Ministry of Justice of the Russian Federation.

Study duration

The one-time study was conducted in May and June 2023.

Experiment description

The shots were fired from fore-end reloading smoothbore shotguns of the Hatsan Escort and Winchester model 1300 Defender 12-gauge with a barrel without a tapered bore (cylinder). The shots consisted of UNO 35E cartridges (Fig. 1) with expanding (frangible) bullets (according to the manufacturer’s declaration) and UNO 35 loaded with bullets without expanding properties, as declared by the manufacturer.

 

Fig. 1. UNO 35E cartridge slug before (left) and after (right) target penetration.

 

The bullets of the specified cartridges were almost completely identical from the design point of view. They were of a full bore, lead, turbine type, 1.8 cm in diameter at the base, 1.8 cm in height, weighing 35±0.1 g, and having a green polymer paint coating on the outside. Into the rear part of the bullets, green polymer shanks were integrated, which could not be separated manually. The visible part of the shank was cylindrical with six wedge-shaped notches in the upper part. The shank diameter at the base was 1.8 cm, and the height of the visible part was 1.8 cm. The fore part of the expanding bullet had a hemispherical depression with a diameter of 0.5 cm and a depth of 0.4±0.1 cm, ensuring its fragmentation into at least five fragments upon hitting the target. The fore part of the bullet without expanding properties had a hemispherical protrusion with a basal diameter of 1 cm and a height of 0.5 cm (Fig. 1).

The targets were multi-component structures consisting of a wooden block (or a rigid substrate made of chipboard), to which biological imitators of the human body, namely parts of a pig carcass (pork belly, brisket with ribs, and breastbone) with a thickness of 5±0.5 cm were attached. These were wrapped in white cotton fabric (coarse calico) with an admixture of viscose (≤5%). Multi-component targets were assembled, representing parts of the pork belly and brisket, separated by a block of sculpted plasticine 3±0.1 cm thick, fixed in a rigid frame, and covered with calico fabric on one side to study the morphological features of the wound channel and exit wounds on the bioimitator skin. The coarse calico and bioimitators were examined visually and metrically to ascertain the dimensional and morphological characteristics of the gunshot damage.

In total, ten shots were fired at the experimental targets with UNO 35 and 35E cartridges. During the experiments, a bullet trap with a kevlar filler was installed behind the targets. The distance from the muzzle of the weapon to the targets in all experiments was 5 m (to exclude the impact of the accompanying factors of the shots).

Methods of recording the outcomes

The process of interaction of the bullets with the targets was video recorded with a Phantom VEO 710S high-speed video camera equipped with a Zeiss Milvus 1.4/35 lens at a frequency of 24,000 frames per second. The dimensions of the experimental gunshot damage were measured with a metal ruler with a 1 mm division value. The gunshot damage was photographed with a Canon PowerShot SX 130 IS digital camera, equipped with a Canon Zoom lens 12xIS 5.0–60.0 mm 1:3.4–5.6, per the rules of forensic and scientific photography.

Statistical analysis

The results were not statistically analyzed.

Ethical considerations

The studies were conducted per the principles outlined in the Helsinki Declaration of the World Medical Association, taking into account the prevailing editions. When analyzing the materials, the requirements of the Federal Law of July 27, 2006, No. 149-FZ were considered¹.

RESULTS

Study objects (participants)

Cuts of cotton calico (20 samples), biological imitator carcasses (30 samples), and plasticine blocks (30 pieces) with experimental gunshot wounds were used.

Main results

Damage to the experimental targets by a bullet of a cartridge without expanding properties. When shooting on experimental targets with a bullet of the UNO 35 cartridge (without expanding properties), through gunshot wounds on the calico and in the tissue material in the form of round-shaped defects with a diameter of 1.7±0.1 cm without radial ruptures were observed in all cases (Fig. 2a). The damage edges were formed by unevenly interrupted, unbraided, and flattened edge threads with deformed fibers interrupted at different levels.

On the skin of biological imitators, the gunshot entry wounds appeared as rounded defects (minus tissue) with a diameter of 1.7±0.1 cm (Fig. 2b). The abrasion collar had a width of ≤0.1 cm. The exit holes had a stellate shape with a centrally located, round tissue defect (minus tissue) with a diameter of 1.8±0.2 cm (Fig. 2c). In the distal part of the gunshot wound lumen, small (≤0.1×0.1×0.1 cm) bullet particles with a polymer coating were identified.

 

Fig. 2. Experimental gunshot damage after firing UNO 35 cartridge: a ― on cotton fabric; b ― an entrance gunshot hole at biological simulator skin; c ― an exit gunshot hole at biological simulator skin.

 

In the plasticine block, the gunshot damage had the form of a tapered expanding channel with oblique longitudinal (relative to the channel axis) tracks, which are a negative display of the relief of the bullet side surface. The entrance holes were round with a diameter of 2.1±0.1 cm. The exit holes were also round but slightly larger, with a diameter of 2.3±0.1 cm.

In the bullet trap behind the target, a bullet with a deformed (expanded to a diameter of 2±0.1 cm) head part with a worn polymer coating was caught.

Damage to the experimental targets with a bullet of a cartridge with expanding (frangible) properties. When experimental targets were hit with bullets from the UNO 35E cartridge, irregular stellate-shaped through-and-through gunshot wounds along with rounded fabric material defects in the center having a diameter of 1.8±0.1 cm were observed on the calico. From the defects, 3–5 radial ruptures with a length of 1.5±0.5 cm were extended, which passed along the warp and weft lines of the material (Fig. 3a). The defect edges were formed by unevenly interrupted, unbraided, and flattened edge threads with deformed fibers interrupted at varying levels. The radial rupture edges were created by unbraided edge threads with elongated fibers interrupted at different levels.

On the skin of the biological imitators, the gunshot entry holes appeared as rounded defects (minus tissue) with a diameter of 1.7±0.1 cm (Fig. 3b). The abrasion collar had a width of ≤0.1 cm. In one-third of the cases, mainly with damage to the biological imitators without bone structures, 3±1 radial skin ruptures with a length of 1±0.5 cm and a depth penetrating up to the muscle tissue extended from the tissue defect edges (Fig. 3c).

In the plasticine block, the gunshot wounds appeared as conically expanding channels with oblique longitudinal (relative to the channel axis) tracks, which are a negative reflection of the lateral surface relief of the bullet, as well as recessed, centrifugally diverging sections with tracks indicating the bullet opening. The entrance holes were round with a diameter of 2.5±0.1 cm. The exit holes were also round but had a slightly larger diameter of 3±0.2 cm.

The formation of 2–5 exit wounds, mostly slit-shaped, measuring 2±0.5×0.5±0.3 cm was registered on the skin (Fig. 3d). An irregularly shaped tissue defect (minus tissue), measuring 0.6±0.4×0.2±0.1 cm was detected in half of the cases; while in the remaining, the exit wounds edges showed no tissue defects. Multiple (≤0.5×0.3×0.2 cm) bullet particles with a polymer coating were found in the distal part of the gunshot wound lumen. In one-third of the cases with damage to several bone-containing structures of the biological simulators (ribs and sternum), blunt-through wounds were formed containing the bullet shank and/or its large-sized fragments measuring 1.7±0.5×1.6±0.1×0.6±0.3 cm in the wound lumen.

 

Fig. 3. Experimental gunshot damage after firing UNO 35E cartridge: a ― on cotton fabric; b ― an entrance gunshot hole without pronounced radial tears at biological simulator skin; c ― an entrance gunshot hole with pronounced radial tears at biological simulator skin; d ― exit gunshot holes at biological simulator skin (marked with red arrows).

 

Bullet fragments were noted in the bullet trap behind the target.

A characteristic comparison of the morphological features of the gunshot wounds of the experimental targets is presented in Table 1.

 

Table 1. Experimental gunshot injuries morphology comparative characteristic

Characteristic	UNO 35	UNO 35E
	without expanding properties	expanding
The shape of the entry injury on the calico	Rounded	Stellate
Radial ruptures in calico	No	Yes, from 3 to 5
The shape of the entry hole on the skin	Rounded	Rounded
Radial ruptures in the skin, spreading from the entry hole	No	Yes, 30% of the cases
Features of the wound channel	Rectilinear, wedge-shaped expanding	Branching
Maximum size of bullet fragments in the wound channel	0.1×0.1×0.1 cm	2.2×1.7×0.9 cm
Exit hole on the skin	Single	Multiple
The shape of the exit hole on the skin	Stellate with a rounded tissue defect (minus tissue) in the center	Mostly slit-shaped with or without a tissue defect
Minus tissue defect in the exit hole on the skin	Yes, corresponding to the diameter of the head of the deformed bullet	Yes, 50% of the cases

 

DISCUSSION

The main differences in the morphological characteristics of the gunshot wounds were determined based on the terminal ballistics of the bullets. Due to the presence of a recess in the head part, the UNO 35E bullet was destroyed upon hitting the biological simulator and its fragments penetrated the tissues as independent missiles, forming several exit wounds. The non-expanding bullet UNO 35 was unfragmented, but only deformed in the head part, forming classical gunshot damage with a rectilinear, tapered expanding channel along the bullet movement and one exit hole. The destruction of UNO 35E transfers a greater part of the kinetic energy in comparison with UNO 35, as indicated by variations in the morphological characteristics of the exit damage. The UNO 35 bullet exits the target with kinetic energy sufficient to achieve penetrating action (minus-tissue defect in 100% of the exit wounds), compared to 50% with the UNO 35E bullet, including blunt-through damage. The high-speed video revealed that (Fig. 4), when an expanding bullet hits, an extensive temporary pulsating cavity is formed in the soft tissues, causing marginal radial ruptures both on the clothing and the skin of the biological imitators adjacent to the entry hole, highly similar to the damage caused in the first zone of the close range of the shot (Fig. 4).

 

Fig. 4. Frame-by-frame reproduction of the target hit process by the UNO 35E cartridge slug.

 

CONCLUSION

The results of this study can be used by experts in the forensic medical identification of structurally similar bullets for 12-gauge (12×70) cartridges, UNO 35 and UNO 35E, based on the morphological features of the gunshot damage they cause to biological tissues and clothing.

ADDITIONAL INFORMATION

Funding source. This study was not supported by any external sources of funding.

Competing interests. The authors declare that they have no competing interests.

Authors’ contribution. All authors made a substantial contribution to the conception of the work, acquisition, analysis, interpretation of data for the work, drafting and revising the work, final approval of the version to be published and agree to be accountable for all aspects of the work. S.V. Leonov, P.V. Pinchuk, A.V. Khodulapov, A.S. Likhachev ― organization and experimental shooting, review and approve the final manuscript; A.V. Khodulapov ― draftig of the manuscript; P.V. Pinchuk, S.V. Leonov, A.S. Likhachev ― critical revition of the manuscript for important intellectual content.

¹ Federal Law of 27.07.2006 N 149-FZ “On Information, Information Technologies and Information Protection” (with amendments and additions). Access mode: https://base.garant.ru/12148555/?ysclid=lztocxd2e4734924924.

About the authors

Pavel V. Pinchuk

Chief State Center for Forensic Medicine and Forensic Expertise 111; The Russian National Research Medical University named after N.I. Pirogov

Email: pinchuk1967@mail.ru
ORCID iD: 0000-0002-0223-2433
SPIN-code: 7357-3038

MD, Dr. Sci. (Medicine), Professor

Россия, Moscow; Moscow

Sergey V. Leonov

Chief State Center for Forensic Medicine and Forensic Expertise 111; Russian University of Medicine

Author for correspondence.
Email: Sleonoff@inbox.ru
ORCID iD: 0000-0003-4228-8973
SPIN-code: 2326-2920

MD, Dr. Sci. (Medicine), Professor

Россия, Moscow; Moscow

Andrey V. Khodulapov

Chief State Center for Forensic Medicine and Forensic Expertise 111

Email: andrey-corsar@yandex.ru
ORCID iD: 0000-0001-7165-2960
SPIN-code: 5174-8374
Россия, Moscow

Artem S. Likhachev

Russian Federal Centre for Forensic Expertise under the Ministry of Justice of the Russian Federation

Email: sbl@sudexpert.ru
ORCID iD: 0000-0003-0816-0204
Россия, Moscow

References

Supplementary files