Assessment of Lead‐Free .22 LR Bullets for Shooting European Rabbits

Abstract

In response to health threats posed by toxic lead to humans and scavenging wildlife, there is currently a focus on transitioning from lead-based to lead-free bullets for shooting (harvesting, culling, or recreational hunting) of wild animals. However, the efficacy of lead-free bullets for shooting small mammals has seldom been evaluated. We compared the animal welfare outcomes and costs of using lead-based and lead-free bullets in the world's most popular cartridge, the rimfire .22 LR, for shooting wild European rabbits (Oryctolagus cuniculus) in Australia, during August 2019. Ballistic testing revealed that lead-free bullets were less precise than one type of commonly used lead-based bullet when shot from one rifle. We shot at 53 and 115 rabbits with lead-based and lead-free bullets, respectively. A substantially lower percentage of rabbits that were hit were wounded (2%) with lead-based bullets compared with lead-free bullets (20%). Hence, fewer shots were needed to kill rabbits with lead-based (1.27) than lead-free (3.98) bullets. Radiographic examination of 28 rabbits shot with lead-based bullets and 27 rabbits shot with lead-free bullets revealed metallic fragments present in 82% and 41% of carcasses, respectively. In 52% of rabbits shot with lead-free bullets, there was no radiographic evidence of bullets or fragments, indicating pass-through shots. The greater cost per bullet and larger number of bullets required to kill a rabbit meant that using lead-free bullets cost 6 times more per rabbit killed than using lead-based bullets. The only commercially available lead-free .22 LR bullets in Australia at the time of our study produced substantially poorer animal welfare outcomes, and were more expensive per killed rabbit, than lead-based bullets. Lead-free bullets designed to reduce lead exposure to scavenging wildlife and humans and should be assessed in terms of animal welfare outcomes and costs prior to being considered for widespread use.

A comparison of fragmenting lead-based and lead-free bullets for aerial shooting of wild pigs

“…Two five-shot groups were measured to assess precision, with group size calculated according to [ 6 , 36 ]. A Caldwell Ballistic Precision ® chronograph (Caldwell Shooting Supplies, Colombia, Missouri, US) ( Fig 1 ) was used to measure bullet velocity at the level of the rifle muzzle and allow calculation of kinetic energy (E K ) at the level of the muzzle (E 0 ) [ 37 ] for 10 shots from each bullet type.…”

“…This was due to inherent difficulties associated with examining animals soon after shooting when using an aerial platform [ 7 , 8 ] and procedural protocols precluding having an observer in the shooting helicopter or the use of worn cameras to collect ante-mortem data [ 42 ]. This also precluded quantifying the frequency of adverse animal welfare events such as non-fatal wounding [ 6 ]. Without an observer aboard the shooting helicopter it was also infeasible to record the numerical range of bullets fired for each animal.…”

“…Radiography is an accepted method in wildlife studies for detecting lead particles [ 3 , 6 , 32 , 47 , 48 ]. The pigs were radiographed using a portable Cuattro ® Slate Plus portable digital radiography system (Cuattro, Golden, Colorado, USA) set at 80 kVp and 2.5 mAs and a wireless 14” x 17” (36 x 43 cm) digital plate [ 6 ]. Standardized lateral radiographs were taken of the left side of each pig with the film centered on the middle of the thorax.…”

“…The radiographs were interpreted by a European board-certified veterinary radiologist (SKJ), who was blinded as to the bullet type used in each film. The presence or absence of metallic fragments or whole projectiles was recorded in radiographs using standard methods [ 6 , 47 , 49 ]. Number of fragments was manually counted to the nearest 10, with a maximum count of 300, i.e.…”

“…Concerns that newly developed bullet technology may not achieve existing animal welfare standards have impeded the adoption of lead-free bullets [ 5 ]. Consequently, there is a requirement for evidence-based assessment of animal welfare impacts for new lead-free bullet technology [ 6 ].…”