Shot is a collective term for small spheres or pellets, often made of lead. These have been projected from slings since ancient times and were the original projectiles for shotguns and are still fired primarily from shotguns and grenade launchers, while they are less commonly used in riot guns. Shot shells are also available in many handgun calibers in a configuration known as "birdshot", "rat shot", or "snake shot".
Lead shot is also used for a variety of other purposes such as filling cavities with dense material for weight and/or balance. Some versions may be plated with other metals. Lead shot was originally made by pouring molten lead through screens into water, forming what was known as "swan shot", and, later, more economically mass-produced at higher quality using a shot tower. The Bliemeister method has supplanted the shot tower method since the early 1960s.
Manufacture
Producing lead shot using a shot tower was pioneered in the late 18th century by William Watts of Bristol, who adapted his house on Redcliffe Hill by adding a three-storey tower and digging a shaft under the house through the caves underneath to achieve a sufficient drop height. The process was patented in 1782. The process was later brought above ground through the building of shot towers.
Molten lead would be dropped from the top of the tower. Like most liquids, surface tension makes drops of molten lead become near-spherical as they fall. When the tower is high enough, the lead droplets will solidify during the fall and thus retain their spherical form. Water is usually placed at the bottom of the tower, cooling the lead immediately upon landing.
Roundness of manufactured shot produced from the shot tower process is graded by forcing the newly produced shot to roll accurately down inclined planes. Unround shot will naturally roll to the side, for collection. The unround shot was either re-processed in another attempt to make round shot using the shot tower again, or used for applications which did not require round shot (e.g., split shot for fishing).
Various hardnesses of the shot can be obtained by using lead alloys containing carefully controlled amounts of tin, antimony, and arsenic. Different alloys also have different melting points. Hardness is also controlled by the rate of cooling.
The , named after inventor Louis W. Bliemeister of Los Angeles, California, (, dated April 11, 1961) is a process for making lead shot in small sizes from about #7 to about #9. In this process, molten lead is dripped from small orifices and falls approximately into a hot liquid, where it then rolls along an incline and then drops another . The temperature of the liquid controls the cooling rate of the lead, while the surface tension of the liquid and the inclined surface(s) work together to bring the small droplets of lead into a highly regular spherical shape. The size of the lead shot that is produced is determined by the amount of lead in each original drip. The diameter of the orifice used to drip the lead has an effect, ranging from approximately for #9 lead shot to about for #6 or #7 shot, as does the specific lead alloy that is used.
The roundness of the lead shot depends on the angle of the inclined surfaces as well as the temperature of the liquid coolant. Various coolants have successfully been used, ranging from diesel fuel to antifreeze and water-soluble oil. After the lead shot cools, it is washed, then dried, and small amounts of graphite are finally added to prevent clumping of the lead shot. Lead shot larger than about #5 tends to clump badly when fed through tubes, even when graphite is used, whereas lead shot smaller than about #6 tends not to clump when fed through tubes when graphite is used.
Lead shot dropped quickly into liquid cooling baths when being produced from molten lead is known as "chilled lead shot", in contrast to "soft lead shot" which is produced by molten lead not being dropped as quickly into a liquid cooling bath. The process of rapidly chilling lead shot during its manufacturing process causes the shot to become harder than it would otherwise be if allowed to cool more slowly. Hence, chilled lead shot, being harder and less likely to deform during firing, is preferred by shotgunners for improving shot pattern densities at longer (> ) ranges, whereas soft lead shot, being softer and more likely to deform during firing, is preferred for improving shot pattern densities at very close (< ) ranges as the softer and now deformed shot scatters more quickly when fired. Soft lead shot is also more readily deformed during the firing process by chokes.
The manufacture of non-lead shot differs from that of lead, with compression molding used to create some alloys.
Sizes
Shot is available in many sizes for different applications. The size of numbered shot decreases as the number increases. In hunting, some sizes are traditionally used for certain game, or certain shooting situations, although there is overlap and subjective preference. The range at which game is typically encountered and the penetration needed to assure a clean kill must both be considered. Local hunting regulations may also specify a size range for certain game. Shot loses its velocity very quickly due to its low sectional density and ballistic coefficient (see external ballistics). Generally, larger shot carries farther, and does not spread out as much as smaller shot.
Buckshot Buckshot is a shot formed to larger diameters so that it can be used against bigger game such as deer, moose, or caribou. Sizes range in ascending order from size #B (0.17 in, 4.32 mm) to Tri-Ball. It is usually referred by the size, followed by "buck", e.g. "#000" is referred to as "triple-aught buck" in the United States or "triple-o buck" in other English speaking countries. Buckshot is traditionally swaged (in high volume production) or cast (in small volume production). The Bliemeister method does not work for shot larger than #5 (0.12 in, 3.05 mm), and works progressively poorly for shot sizes larger than about #6.
Lead shot comparison chart Below is a chart with diameters per pellet and weight for idealized lead spheres for U.S. Standard Designations with a comparison to English shot sizes.
U.S. Size U.K. Size Type Mass (grains) Pellets per oz (lead)Pellets per oz (steel) Diameter (in) Diameter (mm) 0000 Buck 82 0.38 9.65 000½ Buck 76 0.37 9.4 000 LG Buck 70 6n/a 0.36 9.14MG (mould)Buck62.57n/a0.3478.81 00½ Buck 59 0.34 8.64SGBuck54.78n/a0.3328.43 00 Buck 53.8 8 0.33 8.38 0 Buck 49 9 0.32 8.13 #1½ Buck 44.7 0.31 7.87 #1 Buck 40.5 10 0.30 7.62Special SGBuck39.811n/a0.2987.57 #2½ Buck 36.6 0.29 7.37 #2 Buck 29.4 14 0.27 6.86SSGBuck29.1715n/a0.2696.83 #3½ Buck 26.3 0.26 6.6 #3 Buck 23.4 18 0.25 6.35SSSGBuck21.8920n/a0.2456.22 #4 Buck 20.7 21 0.24 6.1 FF Waterfowl 18.2 0.23 5.84SSSSGBuck17.5025n/a0.2275.77 F (or TTT) Waterfowl 16.0 0.22 5.59SSSSSG or AAAABuck/ Waterfowl14.5830n/a0.2145.44 TT Waterfowl 13.9 ~31 0.21 5.33AAAWaterfowl12.535n/a0.2035.16 T Waterfowl 12.0 n/a53 0.20 5.08AAWaterfowl10.9440n/a0.1944.93 BBB Waterfowl 10.2 n/a61 0.19 4.83 BB A or BBBB Waterfowl 8.75 5072 0.18 4.57 B BBB Waterfowl 7.29 – 7.40 6086 0.17 4.32BBWaterfowl6.2570n/a0.1614.09 #1 B Waterfowl 5.47 80103 0.154 3.91 #2 Waterfowl 4.86 90125 0.15 3.81#1Waterfowl4.38100n/a0.1433.63 #3 #2 Waterfowl 3.65 120154 0.135 3.43 – 3.56 #4 Waterfowl 3.24 135192 0.13 3.3#3Waterfowl3.12140n/a0.1283.25 #4½ Bird 2.90 0.125 3.18 #5 #4 Bird 2.57 170243 0.12 3.05#4½Bird2.19200n/a0.1132.87 #6 #5 Bird 1.94 – 1.99 220 – 225317 0.11 2.79#5½ (m.g.)Bird1.82240n/a0.1072.72#6Bird1.62270n/a0.1022.59 #7 #6½ Bird 1.458 300420 0.10 2.54#7Bird/Clay1.29340n/a0.0952.41 #7½ Bird/Clay 1.25 350490 0.095 2.413 #8 Bird/Clay 1.067 410577 0.09 2.286 #8½ #8 Bird/Clay 0.97 450n/a 0.085 – 0.087 2.16 – 2.21 #9 #9 Bird/Clay 0.748 580 – 585n/a 0.08 2.032 #9½ Bird/Clay 0.63 0.075 1.91 #10 #10 Pest 0.51 850n/a 0.07 1.78#11Pest0.421,040n/a0.0661.68#12Pest0.351,250n/a0.0621.57 #11 Pest 0.32 0.06 1.52 #12 Pest 0.183 2,385n/a 0.05 1.27DustPest0.172,600n/a0.0481.22 Dust Pest 0.10 or less 0.04 1.02
Applications outside firearms
When used as a pourable/mouldable weight, lead shot may be left loose, or mixed with a bonding agent such as epoxy to contain and stabilize the pellets after they are poured.
Some applications of lead shot are:
As ballast in various situations, especially where a dense, pourable weight is required. Generally, small shot is best for these applications, as it can be poured more like a liquid. Completely round shot is not required.
Stress testing: Providing variable weights in strength-of-materials stress-testing systems. Shot pours from a hopper into a basket, which is connected to the test item. When the test item fractures, the chute closes and the mass of the lead shot in the basket is used to calculate the fracture stress of the item.
Hydrometers: use a weight made of shot, since the weight has to be poured into a narrow glass vessel.
Split shot, a larger type of lead shot where each pellet is cut part-way through the diameter. This type of shot was formerly commonly used as a line weight in angling. They are no longer solely manufactured from lead but instead are often made from softer materials that can be easily pressed onto the fishing line instead of being closed in a crimp using pliers, as was once common.
The heads of some dead blow hammers are filled with shot to minimize rebound off the struck surface.
Shot belt: some scuba diving weight belts contain pouches filled with lead shot.
Many blackjacks and saps use lead shot as a flexible weight to deliver high energy blows while minimizing damage from sharp impact force (similar to the way it is used in dead blow hammers).
Loudspeaker stands can be filled with lead shot for additional acoustic decoupling, as well as stability.
Model rocketry: to add weight to the nose of the rocket, increasing the stability factor.
Due to its heat capacityAccording to Dulong–Petit law heat capacity of metals is coursely proportional to mass. and low thermal conductivity at low temperatures, lead shot has been used as a suitable material for a regenerator in Stirling engines and thermoacoustic cryocoolers.
Due to lead's high density, it is used to attenuate radiation, especially X-rays and gamma rays. Lead shot may be enclosed in a vest, blanket, or bag that is placed around a point source for radiation shielding.
Bird lead poisoning
Lead shot-related waterfowl poisonings were first documented in the US in the 1880s; by 1919, the spent lead pellets from waterfowl hunting were positively identified as a major source of deaths of bottom-feeding waterfowl.Federal Cartridge Company Waterfowl and Steel Shot Guide. Volume I; 1988.Sanderson, Glen C. and Frank C. Bellrose. 1986. A Review of the Problem of Lead Poisoning in Waterfowl. Illinois Natural History Survey, Champaign, Illinois. Special Publication 4. 34pp. full report from scholar.google.com (cache)A.M. Scheuhammer and S. L. Norris. 1996. "The ecotoxicology of lead shot and lead fishing weights" Ecotoxicology Vol. 5 Number 5 pp. 279-295 Once ingested, stomach acids and mechanical action cause the lead to break down and be absorbed into the body and bloodstream, resulting in death. "If a bird swallows only one pellet, it usually survives, although its immune system and fertility are likely to be affected. Even low concentrations of lead have a negative impact on energy storage, which affects the ability to prepare for migration." Upland game birds such as mourning doves, ring-necked pheasants, wild turkey, northern bobwhite quail and chukars can also ingest lead and thus be poisoned when they feed on seeds.