Evaluating the effect of barrel length on pellet distribution patterns of sawn-off shotguns

Matthieu Maitre; Analisa Chiaravalle; Mark Horder; Scott Chadwick; Alison Beavis

doi:10.1016/j.forsciint.2021.110685

Evaluating the effect of barrel length on pellet distribution patterns of sawn-off shotguns

Forensic Sci Int. 2021 Mar:320:110685. doi: 10.1016/j.forsciint.2021.110685. Epub 2021 Jan 11.

Authors

Matthieu Maitre¹, Analisa Chiaravalle², Mark Horder³, Scott Chadwick², Alison Beavis⁴

Affiliations

¹ Centre for Forensic Science, University of Technology Sydney, Broadway, NSW, 2007, Australia. Electronic address: matthieu.maitre@uts.edu.au.
² Centre for Forensic Science, University of Technology Sydney, Broadway, NSW, 2007, Australia.
³ NSW Police Force, Sydney, Australia.
⁴ Centre for Forensic Science, University of Technology Sydney, Broadway, NSW, 2007, Australia; Faculty of Science, UNSW Sydney, Kensington, NSW, 2052, Australia.

PMID: 33477005
DOI: 10.1016/j.forsciint.2021.110685

Abstract

In recent years, sawn-off shotguns have been regularly encountered in firearm-related incidents. Shotgun represents a community threat due to their ability to be shortened in order to improve their concealability. In practice, forensic scientists and investigators may be asked to determine if a shotgun used in a particular event might have been shortened based on the pellet distribution. To investigate the effect of altering the barrel length on pellet distribution, five 12-gauge shotguns were progressively shortened. Each shotgun was assessed at six barrel lengths and a single discharge of No. 4 shot shotshell ammunition was fired at a fixed fabric target. The shotguns were positioned at six different distances from target and experiments conducted in triplicate. The fabric targets containing pellet pattern underwent data analysis to calculate the pellet distribution area. At short distances from target (≤ 1.0 m), the pellet penetration was observed as a single entry point as the pellets did not have a sufficient flight time to spread from each other. For distances of 2.5 m, 5 m and 10 m, pellet penetration patterns were observed and a quantitative analysis was performed on the samples containing pellet distribution patterns. At each of these distances, it was detected that there was a noticeable increase in pellet distribution area between the unaltered shotgun and altered barrel lengths for all shotguns. The distance from the target as well as the presence of a choke in the shotgun's barrel was found to have a greater impact on the pellet distribution than the barrel length.

Keywords: Firearm investigation; Pellet area; Sawn-off; Shooting distance; Shotgun.