Lead bullet fragments pose a health risk to scavengers and hunters consuming game meat, but lead or lead-core bullets are still commonly employed for big and small game hunting. Bullet fragmentation has been assessed for modern, high-velocity rifles, but has not been well documented for black-powder cartridge rifles or muzzleloading firearms. We used two established methods to estimate bullet fragmentation. We evaluated a traditional .54 round ball and a modern-designed .54 conical bullet for muzzleloaders, two types of .45-70 black powder rifle cartridges, and a modern lead-core high-velocity bullet (.30-06) as our comparison control. We tested penetration and fragmentation in water (n = 12) and ballistics gel (n = 2) for each bullet type. We measured lead mass lost to fragmentation and x-rayed ballistic gels to visualize fragmentation patterns. The modern .30-06 bullets we tested (Remington Core-Lokt) retained a mean of only 57.5% of original mass, whereas mean retention by muzzleloader and black powder cartridge bullets ranged 87.8-99.7%. Round balls and .45-70 bullets shed less lead (i.e., 0.04g and 0.19g on average respectively) than the modern conical .54 muzzleloading bullets (3.08g) or the .30-06 control (4.14g). Fragments from round balls and black powder cartridge bullets showed far less lateral spread compared to the high-velocity modern bullet. Our findings suggest that round balls for muzzleloaders and black powder cartridge bullets may leave far fewer lead fragments in game than the conical muzzleloader bullet or modern high-velocity rifle bullet we tested, and thus could pose a lower risk of secondary lead poisoning for humans and wildlife. Artificial tests cannot replicate conditions encountered in the field, but the striking differences we observed in bullet fragmentation even under severe testing conditions suggests that follow-up tests on game animals may be warranted.
Although lead shotgun ammunition has been banned for waterfowl hunting in the United States since 1992, lead rifle ammunition is still commonly employed for big and small game hunting. However, there is increasing concern that fragments from lead rifle bullets that remain in game meat after butchering pose a health risk to hunters that consume the meat (Goyer 1993; Legget 1993; Hunt et al. 2009; Kosnett 2009). Moreover, lead fragments remaining in viscera removed during field dressing (hereafter, gut piles) or animals shot but not recovered by hunters have been identified as a cause of elevated lead concentrations in wildlife species that scavenge (Haig et al. 2014). Lead concentrations documented in wild animals have varied among species, circumstances, and individual characteristics (e.g., age class-specific foraging) including indications of elevated, acute, and chronic exposures to lead ingestion (Haig et al. 2014).
Whereas earlier work focused on waterfowl and lead shotgun pellets (e.g., Anderson et al. 2000), most subsequent investigations have focused on avian predators, scavengers, and granivores (Pain and Amiard-Triquet 1993; McBride et al. 2004; Hunt et al. 2006; Craighead and Bedrosian 2008; Helander et al. 2009; Hernández and Margalida 2009; Rogers et al. 2012; Haig et al. 2014; Warner et al. 2014). Lead bullet fragments in carcasses and gut piles from big game hunting are a major source of mortality for California condors (Church et al. 2006; Cade 2007; Stauber et al. 2010; Cruz-Martinez et al. 2012; Finkelstein et al. 2012; Rideout et al. 2012), leading to voluntary restrictions on the use of lead ammunition for hunting in Arizona and Utah (Arizona Game and Fish Department, Condors and Lead summary, Reference S1, http://www.azgfd.gov/w_c/california_condor_lead.shtml) and mandatory restrictions in parts of California (Green et al. 2009; Kelly et al. 2011; California Code of Regulations 2015, Reference S2 http://www.fgc.ca.gov/regulations/current/mammalregs.aspx#250_1), now being phased in statewide (Haig et al. 2014). Proposals to restore condor populations in other parts of their historic range would likely depend on strategies to reduce the risk of lead exposure (Yurok Tribe Wildlife Program 2016, Reference S3, http://www.yuroktribe.org/departments/selfgovern/wildlife_program/condor/condorproject.htm; U.S. Fish and Wildlife Service 2013, Reference S4 https://www.fws.gov/cno/es/CalCondor/PDF_files/EXPANSION-CONDOR-RECOVERY-TO-NEW-SITE.pdf ), and concern about lead poisoning of eagles and other scavenging species has led to proposals to ban rifle ammunition containing lead for hunting elsewhere in the United States. For example, effective in July 2008, California modified methods of take for big game and nongame species to exclude use of projectiles containing lead within the designated range of California condors. More comprehensive regulation changes were legislated in 2013, resulting in a state-wide ban on take of wildlife with lead-containing ammunition, with implementation phased in from 2015 to 2019 (https://www.wildlife.ca.gov/hunting/nonlead-ammunition). Colorado's citizen proposal for a ban was rejected in November of 2014 http://www.gjsentinel.com/outdoors/articles/not-taking-the-lead-mdash-yet. In Minnesota, proposed rules that could restrict use of lead-based ammunition for hunting in parts of that state as soon as the 2018 hunting season are currently being debated (see http://www.twincities.com/2016/02/21/minnesotas-lead-ammo-ban-plan-ignites-fiery-debates-among-hunters/). These examples help highlight the diversity of approaches, outcomes, common hunter concerns, and geographic scope of these issues.
Recent research on lead fragmentation and the risk of subsequent ingestion by wildlife or humans has focused on the most common type of modern hunting ammunition used for big game hunting: high-velocity (typically >2400 feet per second [732 m/s]) rifle cartridges that use clean-burning “smokeless” gunpowder, introduced c. 1900 (e.g., Grund et al. 2010; Box 1). For hunting purposes, these cartridges are typically loaded with “conical” bullets (Box 1), actually cylindrical with a tapered tip, containing a lead core partly surrounded by a jacket made of copper, copper alloy, or some other metal harder than lead (Figure 1). The jacket helps keep the bullet intact in the barrel and allows controlled expansion of the soft lead core after impact, creating a large wound channel. Bullet performance (accuracy, mass retention, and penetration) is highly variable, but many common lead-core jacketed bullet designs shed large numbers of small lead fragments when they strike tissue; those small fragments may travel far from the wound channel making it possible that they would be retained in meat from butchered carcasses (Hunt et al. 2009). Lead-free alternatives for high-velocity rifle bullets are typically made of copper or copper alloys and are also designed for rapid expansion in order to kill game quickly and efficiently (Epps 2014).
Ball: a spherical lead bullet traditionally used in smoothbored and rifled muzzleloading firearms; certain types of conical modern military bullets are still referred to as “ball” because of the long history of military use of spherical projectiles during the muzzleloading era (pre-1866).
Black powder: gunpowder made from charcoal, potassium nitrate, and sulfur, widely used in firearms until c. 1900, and still used in many modern muzzleloading firearms, as are “black powder substitute” powders with similar properties.
Black powder cartridge: Self-contained ammunition including a metal case that contains primer, powder, and a typically large-caliber lead bullet, designed for use with black powder and used c. 1865-1900 until superseded by cartridges designed for smokeless powder that used smaller-caliber bullets designed to withstand higher velocities. Black powder cartridges are still used in the modern era but in some cases are loaded with smokeless powder. Such smokeless powder loads are usually designed to produce velocities similar to those possible with blackpowder, so as not to exceed pressure limitations for older firearms.
Bullet: a single projectile fired from a rifle, pistol, or smoothbored firearm.
Caliber: Nominally, diameter of the bore of a rifled firearm, although caliber designations in cartridge names are not always accurate; bore diameter in smoothbored firearms is occasionally designated in caliber but more commonly in gauge (see below)
Cartridge: In modern usage, a self-contained ammunition including a metal case that contains primer, powder, and bullet; in the muzzleloading era, this term was used to describe paper tubes containing a single charge of powder and a bullet that were torn open before use.
Conical: A bullet with length exceeding its width, usually with one end pointed or rounded; conical bullets must be fired from a rifled barrel in order to stabilize and not tumble in flight.
Muzzleloader: A firearm that must be loaded from the front of the barrel (muzzle), using loose ammunition components including black powder (see above) and a ball or bullet that must be handled separately and pushed down to the breech (rear) using a ramrod (slender rod carried with the rifle), and ignited using a percussion cap (see below) or other source of ignition. Muzzleloaders largely were rendered obsolete with the widespread acceptance of metallic cartridges c. 1865, but use and manufacture of these firearms has continued to the present day.
Patch: A piece of cloth, leather, or paper used to wrap around a round ball or occasionally a conical bullet to engage the rifling and cause the bullet to spin when fired.
Percussion: Type of ignition system for a muzzleloader that uses a small metal cap containing a tiny amount of impact-sensitive powder; the cap is struck on firing, explodes, and ignites the main powder charge.
Rifle: A firearm designed to fire a single projectile with spiraling grooves in the barrel that stabilize the bullet in flight allowing greater accuracy; modern rifles using metallic cartridges load at the breech (rear) of the barrel and thus force the bullet to engage the rifling when fired, but muzzleloading rifle bullets must be wrapped in soft material such as a patch (see above) or sabot (see below) so that the bullet engages the rifling while still allowing the rifle user to easily push the bullet down the barrel from the muzzle.
Rifling: Spiraling grooves in the barrel of a rifle or pistol that impart stabilizing spin to bullets.
Sabot: A thick jacket of plastic, wood, or other soft material around a conical bullet that engages the rifling and in some cases allows shooting a bullet of smaller caliber in a given barrel, thereby increasing velocity and protecting the bullet from damage by the barrel itself; some modern muzzleloading ammunitions including the typical currently available lead-free designs require the use of a sabot in order to engage the rifling when loaded from the muzzle.
Shot: Small pellets (typically 2-5mm diameter) made of lead, steel, or other metals, fired in large numbers per discharge from a shotgun or other smoothbored firearm; shot is usually used for hunting birds and small mammals of up to a few kilograms in weight, although larger diameter “buckshot” pellets may be used for hunting big game animals.
Shotgun: A firearm lacking rifling (above), designed to fire multiple pellets of shot (see above) simultaneously. Shotguns can also be used to fire a single projectile known as a “slug” that may be used for big game hunting.
Smokeless powder: a wide variety of gun powders developed in the late 19th century and used through the modern era; smokeless powders burn more cleanly and can achieve higher velocities than black powder.
Smoothbore: A firearm lacking rifling and designed to fire a single ball, multiple smaller balls, or shotgun pellets; typically, this term is used to identify muzzleloading firearms of that description rather than modern shotguns.
Twist: The rate at which rifling spirals within a rifle barrel, commonly reported as the ratio of 1 full turn to the number of inches required for a full turn, e.g., 1:48 (1:122 cm); typically, longer conical bullets require “faster” twists where a full turn occurs in a shorter distance.
The risk of lead toxicity to wildlife or humans from game carcasses of animals killed with muzzleloading firearms (hereafter muzzleloaders; Box 1) has received little attention despite the popularity of this type of hunting. Most states in the United States have separate big game hunting seasons for muzzleloaders, either rifled or smooth-bored (lacking rifling; Box 1), firing a single projectile. Muzzleloader-only seasons have become popular for hunters seeking to challenge themselves through use of a shorter-range weapon or interested in additional hunting opportunities, and some states allow black powder cartridge rifles (pre-1900 designs that originally used black powder and large caliber lead bullets and are thus ballistically similar to muzzleloaders; Box 1) to be used during those seasons (Epps 2014). Although current data are lacking, surveys in the late 1990s suggested that 30% of licensed hunters in the United States use muzzleloaders at some point (Duda et al. 1998).
Muzzleloaders use “black powder” (made from charcoal, potassium nitrate, and sulfur; Box 1) or substitutes with similar burning characteristics as propellants, are loaded from the muzzle using loose components rather than self-contained cartridges, and fire bullets at much lower velocities (typically <1800 feet per second [549 m/s]) due to the limitations of black powder. Traditional hunting bullets for muzzleloaders are round balls (Box 1) made of pure lead and wrapped in a cloth patch to engage the rifling (Figure 1a); because of the low velocity and low potential for expansion, larger calibers (≥.45 rather than ≥ .22 or .23 as required for modern high-velocity rifles) are required by most states' hunting regulations for muzzleloaders used to hunt large game animals. Muzzleloading rifles can be loosely divided into two basic types: the first copies traditional 18th and 19th century designs to varying degrees (hereafter, “traditional” muzzleloaders, e.g., Figure 2a), while the second uses modern materials and designs while maintaining the basic requirement that the firearm be loaded at the muzzle with loose components (i.e., powder and bullet are not contained in a cartridge; hereafter, “modern” muzzleloaders). Although we were unable to locate more recent data or estimates of nation-wide trends, a 1999 survey found that 69% of muzzleloader hunters in South Dakota used traditional muzzleloaders and 31% used modern muzzleloaders (Boulanger et al. 2006), suggesting that both types see widespread use.
Several types of lead-free bullets for muzzleloaders are available, but most require long conical designs to achieve sufficient projectile weight from materials less dense than lead, and often require the use of sabots (plastic wrappers, Box 1) to engage the rifling (e.g., Figure 1e). Such conical bullets cannot be used in smoothbores and typically require specialized rifle barrels with very rapid rates of twist (e.g., rifling that spins the bullet one turn in 15-34 inches [38.1-86.4 cm], reported as a 1:15-1:34 twist; Box 1) to achieve suitable accuracy (Roberts 1940, p. 14). Some modern muzzleloaders have very fast-twist barrels to enhance accuracy of conical bullets. However, traditional and many modern muzzleloading rifles typically have twist rates of 1:24-1:70, with 1:48 being the most common (Roberts 1940, p. 14). Thus, long conical bullets used in those firearms will have poor accuracy or tumble end-over-end, preventing expansion upon striking. Moreover, some states (e.g., Oregon; Oregon Department of Fish and Wildlife, 2015, p. 20, Reference S5, http://www.dfw.state.or.us/resources/hunting/index.asp#Rules) have banned use of long conical bullets and bullets with sabots in muzzleloaders during muzzleloader-only hunting seasons, in an effort to restrict hunters to more primitive (traditional) technology. Non-lead bullet options are available for some common blackpowder cartridge rifles, but are limited in availability and may perform very differently from the solid lead bullets for which those rifles were designed (Epps 2014). Therefore, as the debate about regulation of lead ammunition for big-game hunting continues, hunters and regulators dealing with muzzleloaders and blackpowder cartridge rifles are faced with several problems: 1) traditional and some modern muzzleloaders may not fire most existing lead-free bullet designs accurately enough to reliably kill game animals, and non-lead options for blackpowder cartridge rifles have largely been ignored by manufacturers to date; 2) regulations restricting bullet length may preclude the use of many existing designs of lead-free muzzleloader bullets in some states; 3) the potential risk of lead exposure for wildlife and humans from meat harvested by muzzleloading firearms and blackpowder cartridge rifles using lead bullets is unclear, as recent studies have focused on modern high-velocity rifle bullets of radically different design (e.g., Hunt et al. 2006; Hunt et al. 2009; Trinogga et al. 2013).
In this paper we address one aspect of this problem by assessing lead fragmentation of two types of muzzleloader ammunition relative to a typical modern lead-core high-velocity rifle bullet. Secondly, we assess lead fragmentation for two types of black powder cartridges (Box 1). Based on projectile structure and velocity, we predicted that lead fragmentation (number of fragments and amount of weight lost by the bullet after striking simulated tissue) would be much lower for bullets fired from both muzzleloader and black powder cartridges than for the modern high-velocity rifle bullet, and designed our tests to maximize fragmentation to fully test this hypothesis. Although artificial tests cannot replicate hunting conditions (Caudell 2013), results of this work will contribute to assessment of potential risks for lead exposure to scavengers and human consumers of wild game meat harvested with muzzleloaders or black powder rifles.
We chose three commonly-used types of firearms suitable for big game hunting: a .54 caliber traditional muzzleloading rifle with slow-twist rifling (1:70; bore diameter 13.72 mm), a .45-70 black powder cartridge rifle (bore diameter 11.43 mm), and a .30-06 rifle (bore diameter 7.62 mm; Table 1; Figure 2). We tested five types of rifle ammunition (Table 1; Figure 2), including 1) traditional .54 round balls made of pure lead for muzzleloaders, 2) modern-designed .54 conical bullets for muzzleloaders made of pure lead with a shallow hollow point to encourage expansion (Buffalo Bullet™, Lyman Products, Middleton, CT, United States of America), 3) Goex BlackDawge™ .45-70 cartridges loaded with black powder and a 405gr lead-alloy bullet (mixed with a small amount of tin or antimony to harden it, as is typical for black powder cartridge bullets), 4) Ultramax™ .45-70 cartridges loaded with a modern smokeless powder to low velocities typical of blackpowder and a 405gr hardened lead-alloy bullet, and 5) conventional modern .30-06 Remington cartridges loaded with Core-Lokt™ 150gr lead core bullets with a copper alloy jacket.
We estimated lead fragmentation from five types of rifle ammunition by firing bullets into two well-established types of media for fragmentation testing: plastic milk jugs filled with water and ballistic gelatin. We used the water jug method because it allowed for easy recovery of all bullet fragments and made it easier to precisely estimate mass loss to fragmentation. We used a limited number of ballistic gelatin trials to allow visualization of fragmentation patterns by x-ray and qualitative comparisons, but because of the expense and time-consuming nature of this technique, did not attempt to conduct sufficient tests for statistical comparisons. We conducted our trials on a private range in Shedd, Oregon, May-August, 2012.
For the water jug trials, we used a Sartorius Element ELT-103 scale (Sartorius, Arvada, CO, USA) to measure the mass of individual bullets for the muzzleloader prior to field trials and then stored the rounds in uniquely labeled plastic bags. For the rifles using cartridges (both blackpowder and smokeless), we pulled and measured eight bullets from cartridges in the same box or lot of each type of ammunition used in the firing trials, and estimated mean mass after wiping off any soft lubricant. We used an adjustable wooden brace to hold a 60-gallon plastic drum and aligned five 1-gal jugs on a leveled wooden platform within the drum. We cut a hole into the removable watertight lid to allow entry of the bullets into the test chamber and placed the front edge of the drum 9.14m (30ft) from the shooting bench. By positioning the target 9.14 m from the firearm muzzle, we created a test situation that models the “best case” scenario for a traditional weapons hunter with regards to prey proximity, but the “worst case” scenario with respect to ammunition fragmentation, which is most likely to occur at close range where velocity is higher. Moreover, although the short testing distance likely increased potential for fragmentation beyond many hunting situations, we considered this appropriate given our hypothesis that muzzleloader and black powder cartridge bullets were less likely to fragment. The penetrating power of .45-70 ammunitions (smokeless and black powder) resulted in bullets completely penetrating and exiting our first test chamber. Therefore, we used a second test chamber placed immediately behind the first so that the bullet would encounter up to 10 water jugs; we affixed two 30.5cm x 30.5cm pieces of 1.9 cm plywood to the inside back of the second drum to ensure bullet capture for the .45-70. We positioned a digital chronograph (Competition Electronics ProChrono, Rockford, IL, USA) midway between the shooting bench and the test chamber in order to measure projectile velocities. We attempted to collect velocity measurements for 12 replicates of the .30-06 ammunition and the first six replicates of each of the others.
After firing, we used standard window mesh and a five-gal bucket to sieve stray fragments, while collecting all major fragments from the drum and sometimes from within the water jugs themselves. We recorded how many water jugs were pierced and the bullet velocity for each round. We air-dried and then measured the mass of the largest remaining fragment and calculated mass retention (percent). We completed 12 replicate trials with each of the .54 round ball, .54 conical, and .30-06 ammunitions and six replicate trials with each of the .45-70 cartridges (i.e., black powder and smokeless powder; we limited those trials because we expected both types of .45-70 cartridge to behave similarly despite the different propellant). We used a Wilcoxon test to determine whether means of the two .45-70 cartridge types differed; finding no significant difference, we planned to group the .45-70 data points when performing a one-way ANOVA on measurements of mass lost (g). We used Tukey's post-hoc tests to identify between-group differences.
Our second method of testing bullet fragmentation was to fire bullets into blocks of ballistic gelatin (Vyse Professional Ballistic and Ordnance Gelatin, Gelatin Innovations, Schiller Park, IL, USA). This approach allowed us to estimate lateral spread of lead fragments from the main track of the bullet, and visualize patterns of fragmentation by radiograph. Ballistic gelatin also is usually regarded as more similar to tissue than water, although it does not simulate the effect of bullets striking bone which can contribute to bullet fragmentation in game animals. Using the same drum arrangement and distance (9.14m), we placed two gel blocks (40.6cm x 15.2cm x 15.2cm) end-to-end on the leveled platform within the drum and fired the bullet into one end. We performed two replicate trials of the round ball (.54 caliber), conical (.54 caliber), and .30-06 ammunitions, but only one trial of the .45-70 blackpowder cartridge (loaded with blackpowder, as that load produced more velocity than the smokeless load we employed (Table 2) because bullets penetrated too deeply to be captured by the gel, although fragmentation in the gel could still be evaluated. We radiographed gels at the Veterinary Diagnostics Laboratory (College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA). We measured bullet track length, estimated the number of lead fragments (precise counts were not feasible because some fragments obstruct others in any given x-ray image), and estimated the perpendicular distance between the bullet track and the two fragments farthest (laterally in 2 planes) from the track. Although fragments were more difficult to recover in this method, for each test round, we extracted the largest remaining fragment and compared its mass to those resulting from similar rounds fired through water.
Projectile velocity and bullet penetration varied among the ammunitions we tested (Table 2). Due to the chronograph shifting during one test, we obtained only 11 estimates of velocity for the .30-06. In the water jug tests, the conical .54 bullets pierced an average of 4.4 (SD = 0.5) jugs, while .30-06 and .54 round balls pierced an average of 3.8 (SD = 0.4) and 3.3 (SD = 0.6), respectively (Table 2). Both smokeless and black powder .45-70 rounds consistently penetrated 10 water jugs and lodged in the backstop material. In ballistics gels, the black powder .45-70 bullet penetrated most deeply (n = 1, exited gel after penetrating 81.2 cm), followed by the conical .54 bullets (n = 2, x = 60.5 cm), the .30-06 bullets (n = 2, x = 40.0 cm) and the round balls (n = 2, x = 39.8 cm).
Mass loss (g) and thus fragmentation varied significantly among the muzzleloading and black powder bullets we tested (Table 2). Results of the Wilcoxon test (Z = 0.08006, P = 0.9362) indicated that mass lost (g) by the two types of .45-70 ammunition did not differ and therefore we combined them when performing the ANOVA, which indicated a significant difference (F (3, 44) = 23.463, P ≤0.0001). Post-hoc Tukey's tests revealed that mass lost (g) did not significantly differ (P = 0.304, M = 1.064) between the conical .545 and .30-06 bullets (Figure 4). Mass lost (g) by conical .545 bullets was significantly different (P ≤ 0.0001) from that of both the roundball .54 (M = 3.039) and the grouped .45-70 bullets (M = 2.887); similarly, mass lost (g) by the .30-06 bullets differed significantly (P ≤ 0.0001) from that of both the roundball .54 (M = 4.103) and grouped .45-70 (M = 3.951) bullets. The .30-06 rounds fragmented extensively in the water jug tests, retaining an average of only 57.5% of their original mass and producing large quantities of tiny fragments (Table 2; Figure 3a). Among the muzzleloading and black powder cartridge bullets, mass retention was lowest for the .54 conical rounds (x̄ = 87.8%), which frequently broke into several large fragments with some small particles (Table 2; Figure 3b). Mass retention was high for the .54 round balls (x̄ = 99.7%; Table 2, Figure 3c), the .45-70 black powder cartridges (x̄ = 99.3%, Table 2, Figure 3d), and the .45-70 smokeless cartridges (x̄ = 99.3%, Table 2, Figure 3e).
Both .54 round balls and standard .30-06 bullets recovered from gel blocks demonstrated lead retention similar to or marginally greater than that observed in the water trials (Table 2 and see Supplemental Material, Data S1). However, mass retention by the conical muzzleloader bullet varied in our limited number of gel trials. One iteration resulted in mass retention well within the range observed in the water trials (90.4%; Table 2 and see Supplemental Material, Data S1), whereas the other iteration resulted in lower retention (76.2%). Representative radiographs of gels struck by standard .30-06, conical muzzleloader bullets, round ball, and blackpowder cartridge bullets demonstrate visually the range of fragments sizes and bullet tracks created by those types of ammunition (Figure 5). Gels struck by the .30-06 rounds contained ≥ 200 fragments each (Figure 5a); fragments traveled up to 10cm laterally from the bullet track and in some cases exited the sides of the gel (by measuring the two fragments with the farthest lateral travel that remained in the gel for each trial, n = 4, x̄ = 6.6 cm). The .54 round balls expanded but produced <10 visible micro-fragments each besides the ball itself (Figure 5b), whereas the .54 conical bullets expanded and created approximately 50 fragments in the gel (several large and many micro-fragments; Figure 5c). The average distance of fragments from bullet track was similar for the .54 round balls and conical bullets (n = 3, x = 1.8 cm; n = 4, x̄ = 1.8 cm, respectively). Actual loss of lead (mass) in the gel trials varied by bullet type. The greatest fragmented mass was produced by the .30-06, however mass lost to fragmentation also was high and variable for the conical .54 bullet (Table 2). In comparison, the remaining bullets we tested (.45-70 smokeless cartridge, .45-70 black powder cartridge, and round balls) produced far less fragmented mass, retained nearly all their initial weight (Table 2), and left few (roundball, Figure 5b) or no (.45-70, Figure 5d) discernible fragments in the ballistic gelatin.
We assessed the velocity, penetration, and mass retention of a traditional muzzleloader hunting bullet (.54 round ball), a modern-designed muzzleloader hunting bullet (.54 conical with a hollow point), two traditional-style lead bullets loaded in black powder rifle cartridges (.45-70, one type loaded with black powder and another loaded to similar velocity with smokeless powder), and a typical modern lead-core hunting bullet (.30-06). The degree of lead fragmentation differed widely between the different types of firearm and ammunition tested, but the traditional-style bullets in muzzleloader and black powder cartridge rifles that we tested shed a much lower mass of lead fragments than either the modern lead-core hunting bullet or the modern-designed muzzleloader hunting bullet.
As expected, we found that bullet velocity appeared to be positively correlated with fragmentation. Bullet construction also appeared to affect bullet fragmentation. We observed significant variability in fragmentation among muzzleloader and black powder bullets, although all of them fragmented less than the conventional bullets (.30-06; Table 2; Figures 3 and 4). As a likely consequence of the low velocities coupled with non-expanding bullet designs, the muzzleloading round balls and .45-70 bullets shed significantly less lead than the modern-designed conical muzzleloader bullets. Although the conical muzzleloading bullets traveled significantly slower than round balls, their hollow points enabled expansion which made shedding of fragments more likely (Table 2, Figures 3b and 5b). Thus, the conical muzzleloader bullets shed as much lead mass as the high-velocity jacketed soft-point .30-06 bullet, even though the proportional mass loss was lower. However, examination of ballistics-gel radiographs showed that the .30-06 bullet spread more fragments of smaller size through more of the gel volume than did the conical muzzleloader bullet (Figure 5a). The lack of difference in fragmentation for bullets from the two types of .45-70 cartridges (Table 2) demonstrates that smokeless powder per se does not increase fragmentation if velocity is not increased; however, smokeless powder and smaller-caliber jacketed bullets can be loaded to achieve much higher velocity than is possible with black powder.
Bullet performance is complex: penetration and fragmentation can be affected by distance and angle, the interactive effects of powder charge, bullet shape, and weight on velocity, bullet hardness, whether the bullet encounters multiple tissue types including bone and hide, and imperfections in bullet shape (Caudell et al. 2012; Caudell 2013; Epps 2014). Although our trial was limited in the range of conditions and the number of bullet types we tested, it offers valuable insights for management of lead ingestion risk for humans and wildlife. For example, the restricted lateral spread of lead fragments produced by the traditional non-expanding lead bullets suggests that ingestion risk could be relatively low for human consumers of meat harvested with these bullets if meat in the immediate vicinity of the wound track is avoided. When these bullets are used for hunting big game, scavenging wildlife species could be at risk of ingesting the main bullet body or some of the few fragments remaining in the gut pile or discarded carcass. However, because of the low number and spread of fragments, this risk could be reduced by engaging hunters to recover the main remaining body of the bullet in cases where the bullet does not exit the game animal. Further work with additional bullet types, such as non-expanding conical bullets of traditional design, and tests on live game animals (e.g., Trinogga et al. 2013) would improve understanding of fragmentation by traditional bullets in actual hunting situations (see Caudell 2013), the feasibility of managing those risks by engaging hunter cooperation, and whether the small amount of lead shed by primitive bullets is enough to pose a health risk to humans or wildlife. Fragmentation risk of jacketed lead-core bullets used with sabots in muzzleloaders may also be worthy of investigation; for instance, radiographs of an offal pile from a muzzleloader-harvested deer killed with a copper-jacketed lead core bullet yielded 107 lead fragments (Warner et al. 2014). In the absence of additional such studies, and given the popularity of hunting with muzzleloaders and black powder cartridge rifles, we expect that use of lead bullet designs subject to fragmentation, rather than non-lead or less fragmentation-prone traditional bullet designs, could appreciably increase exposure of wildlife to lead in game meat.
Our results also suggest an interesting insight as to how risks from lead exposure changed as Euro-Americans with firearms colonized the continent during and beyond the exploration era. From our results, we hypothesize that exposure to lead fragments could have increased dramatically for scavengers after high-velocity smokeless cartridges with jacketed bullets began to be used ca. 1900, as proposed by D'Elia and Haig (2013, pp. 87-90). However, lead shot (Box 1) was widely used in shotguns and smoothbores for hunting birds and small mammals since colonization by Euro-Americans, leading to potential exposure to lead for animals scavenging those types of carcasses.
As modern hunters, game meat consumers, and wildlife managers seek ways forward on the issue of lead-based bullets, a combination of regulations and voluntary practices might provide a successful solution. Regulations concerning use of lead-based rifle ammunitions vary widely among states and availability of non-lead alternatives varies by type, caliber, and geographic region (Avery and Watson 2009; Oltrogge 2009). As written in Oregon, current (2015) muzzleloader ammunition restrictions preclude use of long conical bullets, bullets with plastic tips, or bullets using sabots (Box 1), thus precluding use of several non-lead muzzleloader bullets currently on the market. Although we did not evaluate fragmentation of jacketed lead-core bullets used with sabots, such bullets are designed to expand and, like the Buffalo Bullet tested in this study, are probably more likely to fragment. Thus, Oregon's restriction likely reduces lead fragmentation created during muzzleloader hunts from that source, although short expanding bullets (such as the Buffalo Bullet tested in this study) are still permitted, while limiting use of existing non-lead options because of the sabot limitation. Changing regulations to allow use of all lead-free bullets regardless of length or need for a sabot would encourage hunters who favor the performance of the lead-free bullets to buy fast-twist muzzleloaders capable of shooting such bullets accurately. That change, paired with encouraging hunters to use lead round balls rather than expanding lead conical bullets for traditional slow-twist rifles or smoothbored muzzleloaders, would reduce lead fragments in carcasses of game animals while ensuring continued participation by an important community of hunters. However, changing regulations may require complex considerations. For instance, as some muzzleloading seasons in Oregon are designed to allow hunting at times of the year when mature bucks may be more visible and vulnerable, there is concern that allowing lead-free conical bullets used with sabots and plastic tips could extend the effective range of muzzleloaders and lead to overharvest of mature bucks (Ron Anglin, ODFW, personal communication). Yet, within the last two years, Oregon has changed regulations to allow non-lead projectiles and copper conical bullets lacking plastic tips or sabots, as previous regulations disallowed both types. Ongoing discussions among hunters, consumers, and rule-makers about lead, fragmentation, lead-free alternatives, and in-field management could promote health of both human and wildlife consumers of game harvested with traditional primitive firearms.
Although a limited trial, our study has significance for hunters, scavengers, and wildlife management decision makers. In our test situation, which likely increased potential for fragmentation due to the relatively short distance between shooter and target but did not include bones or other elements that may influence fragmentation, both solid-lead round balls for muzzleloaders (pure lead) and .45-70 black powder-type bullets (hardened lead alloy) produced far fewer lead fragments and less fragment mass than a commonly-used type of modern designed hollow-point conical muzzleloader bullet or a typical type of jacketed lead-core soft-point .30-06 bullet. This difference results from a combination of bullet velocity and construction.
Under regulations banning use of all lead bullets, users of traditional muzzleloading and black powder cartridge rifles could be excluded from hunting because of current limitations in effective non-lead options for those types of firearms (Epps 2014), and some individuals would be blocked from important cultural and subsistence foraging activities. Similarly, regulations that restrict non-lead bullets prevent muzzleloading hunters from voluntarily avoiding lead and could discourage hunters from buying fast-twist rifles designed to shoot long lead-free bullets with sufficient accuracy. Instead, regulations that allow lead-free bullets of any type (including those which require use of sabots) in addition to traditional non-expanding lead bullet designs could simultaneously reduce lead ingestion risks to humans and wildlife, while also allowing and encouraging primitive weapons hunters to continue participation in hunting.
Data S1. Archive of raw data collected on fragmentation of lead-based projectiles fired from firearms suitable for big game hunting: a .54 caliber traditional muzzleloading rifle with slow-twist rifling (1:70; bore diameter 13.72 mm), a .45-70 black powder cartridge rifle (bore diameter 11.43 mm), and a .30-06 rifle (bore diameter 7.62 mm. We conducted our tests at a private rifle range in Shedd, OR, during May-August 2012. Data types derived from water trials include measures of fragmentation (fraction remaining in large mass; mass lost), projectile velocity, and number of water-filled jugs penetrated by each sample. Additionally, data from limited trials using ballistics gel (mass lost, % mass retained, distance penetrated) are provided for the round ball, conical bullet, and modern .30-06.
Found at DOI: 10.3996/092015-JFWM-086.s1; (15 KB XLSX).
Reference S1. Arizona Game and Fish Department. Condors and Lead website,
Found at http://www.azgfd.gov/w_c/california_condor_lead.shtml (78 KB PDF). Also found at DOI: 10.3996/092015-JFWM-086.s2; (77 KB PDF).
Reference S2. California Fish and Game Commission. California Mammal Hunting Regulations, §250_1Prohibition on the use of lead projectiles and ammunition using lead projectiles for the take of wildlife.
Found at http://www.fgc.ca.gov/regulations/current/mammalregs.aspx#250_1 (15 KB PDF). Also found at DOI: 10.3996/092015-JFWM-086.s3; (14 KB PDF).
Reference S3. Yurok Tribe Wildlife Program, Welcome to the Yurok Condor Program, Yurok Tribe. Found at http://www.yuroktribe.org/departments/selfgovern/wildlife_program/condor/condorproject.htm (26 KB PDF). Also found at DOI: 10.3996/092015-JFWM-086.s4; (25 KB PDF).
Reference S4. U.S. Fish and Wildlife Service. Preliminary issues to be addressed in seeking an expansion of condor recovery to a new site (effective 12/30/13)
Found at https://www.fws.gov/cno/es/CalCondor/PDF_files/EXPANSION-CONDOR-RECOVERY-TO-NEW-SITE.pdf (57 KB PDF). Also found at DOI: 10.3996/092015-JFWM-086.s5; (56 KB PDF).
Reference S5. Oregon Department of Fish and Wildlife. 2015 Oregon big game regulations.
Found at http://www.dfw.state.or.us/resources/hunting/index.asp#Rules (221 KB PDF). Also found at DOI: 10.3996/092015-JFWM-086.s6; (220 KB PDF).
We thank K. Moriarty, S. Sachs, A-M. Meyers, and D. Whittaker for their assistance in the ballistic trials. This work was supported by an award from the Oregon State University Undergraduate Research, Innovation, Scholarship and Creativity (URISC) program to co-author Taylor as well as by start-up funding provided by Oregon State University's College of Agricultural Sciences for co-author Sanchez. Comments by two anonymous reviewers and the editorial staff enabled improvement of this manuscript.
Any use of trade, product, website, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Citation: Sanchez DM, Epps CW, Taylor DS. 2016. Estimating lead fragmentation from ammunition for muzzleloading and black powder cartridge rifles. Journal of Fish and Wildlife Management 7(2):467-479; e1944-687X. doi: 10.3996/092015-JFWM-086
The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.