Lead shot is a collective term for small balls of lead. These were the original projectiles for muskets and early rifles, but today lead shot is fired primarily from shotguns. It is also used for a variety of other purposes. It was originally made by pouring molten lead into wooden molds and later more economically mass-produced using a shot tower.
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Producing lead shot from a shot tower was pioneered by William Watts of Bristol who adapted his house on Redcliffe Way by adding a three-storey tower and digging a shaft under the house through the caves underneath to achieve the required drop. The process was patented in 1782.[1]
The process was brought above ground through the building of shot towers.
Molten lead would be dropped from the top of the tower. Like most liquids, molten lead becomes spherical as it falls. Water is usually placed at the bottom of the tower, causing the lead to be cooled immediately after dropping.
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).[1]
Hardness of lead shot for shotgun shells is controlled through adding variable amounts of antimony and arsenic, forming lead-antimony alloys.[1]
The Bliemeister method, named for Louis Bliemeister, the man who patented it, is a process for making lead shot in small sizes which has largely supplanted the shot tower method. In this process, metered molten lead is dropped approximately 1 in (25 mm) into hot water, rolled along an incline and then dropped another 3 ft (0.91 m). The water temperature controls the cooling rate of the lead, while the surface tension brings the ball into a spherical form. Antimony, added for hardness, also lowers the melting point of lead.[2]
Larger lead shot comes in three sizes: B, BB, and BBB. Smaller lead shot is available in sizes 7½, 8, and 9, with applications ranging from sporting clays and skeet shooting, to non-waterfowl hunting at progressively shorter distances. The larger bird shot sizes (i.e., 6, 5, 4)are mostly used in turkey and pheasant hunting applications where legal. Older shotguns continue to use lead shot, as firing newer, harder, non-lead shot may damage the shotgun, and firing soft metal substitutes for lead shot may not be economical.
Buckshot is simply lead shot formed to larger diameters. Sizes range in ascending order from size B to Tri-Ball.
Below is a chart with diameters per pellet and weight for idealized lead spheres.
| Size | Type | Weight | Diameter |
|---|---|---|---|
| #TriBall(12 Ga.) | Buck | 20.41 g (315 gr.) | 15.24 mm (0.60") |
| #0000 | Buck | 5.51 g (85 gr.) | 9.40 mm (0.380") |
| #000 | Buck | 4.54 g (70 gr.) | 9.14 mm (0.360") |
| #00 | Buck | 3.49 g (53.8 gr.) | 8.38 mm (0.330") |
| #0 | Buck | 3.18 g (49 gr.) | 8.13 mm (0.320") |
| #1 | Buck | 2.62 g (40.5 gr.) | 7.62 mm (0.300") |
| #2 | Buck | 1.91 g (29.4 gr.) | 6.86 mm (0.270") |
| #3 | Buck | 1.52 g (23.4 gr.) | 6.35 mm (0.250") |
| #4 | Buck | 1.34 g (20.7 gr.) | 6.09 mm (0.240") |
| #FF | Buck | 1.18 g (18.2 gr.) | 5.84 mm (0.230") |
| #F (TTT) | Buck | 1.05 g (16.2 gr.) | 5.59 mm (0.220") |
| #TT | Buck | 0.98 g (15.1 gr.) | 5.33 mm (0.210") |
| #T | Buck | 0.89 g (13.7 gr.) | 5.08 mm (0.200") |
| #BBB | 0.66 g (10.2 gr.) | 4.82 mm (0.190") | |
| #BB | 0.57 g (8.8 gr.) | 4.57 mm (0.180") | |
| #B | 0.48 g (7.4 gr.) | 4.32 mm (0.170") | |
| 2 | 3.76 mm (0.148") | ||
| 4 | 3.28 mm (0.129") | ||
| 5 | 3.05 mm (0.120") | ||
| 6 | 2.77 mm (0.109") | ||
| 7.5 | 2.39 mm (0.094") | ||
| 8 | 2.26 mm (0.089") | ||
| 8.5 | 2.16 mm (0.085") | ||
| 9 | 2.01 mm (0.079") | ||
| 12 | rat/snake | 1.3 mm (0.05") |
Lead shot is also often used 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. Some examples applications are:
Due to its relatively high heat capacity and low thermal conductivity at low temperatures, lead shot has been used as a suitable material for a regenerator in stirling or thermoacoustic cryocoolers.
When hunters use lead shot, waterfowl such as ducks can ingest the spent pellets later and be poisoned; predators that eat these birds are also at risk.[3] There are various places in the world (e.g., the Netherlands, the Wetlands in Britain, North American Wetlands) [4] where hunting with lead shot is banned due to the metal's toxicity. For these places, nonlead alternatives have been introduced, using materials such as steel, tungsten-nickel-iron, bismuth-tin, and tungsten-polymer.