Lead shot
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Lead shot is a collective term for small balls of lead. It is used primarily as projectiles in shotguns, but is also used for a variety of other purposes. It was traditionally made using a shot tower.
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[edit] Manufacturing
Lead shot was pioneered by William Watts of Bristol who adapted his house on Redcliff Way by adding a three story tower and digging a shaft under the house through the caves underneath to achieve the required drop. The process was patented in 1782.
The process was brought above ground through the building of shot towers.
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 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).
Hardness of lead shot for shotgun shells is controlled through adding variable amounts of antimony, forming lead-antimony alloys.
[edit] Sizes
Larger lead shot comes in three sizes: B, BB, and BBB. Smaller lead shot is still available in bird shot in sizes 7 1/2, 8, and 9, where it is intended primarily for sporting clays and skeet shooting, or for non-waterfowl hunting at progressively shorter distances. The larger bird shot sizes (e.g., 6, 5, 4) are more difficult to obtain in lead, having been banned for upland waterfowl hunting since the 1970s in the United States, although they are still occasionally seen, remaining legal for uses other than for waterfowl hunting. Older shotguns continue to use lead shot, as firing newer, harder, non-lead shot will damage the shotgun, and firing soft metal substitutes for lead shot is not usually economically-viable.
[edit] Applications outside firearms
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. An example of this application is 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 also often use a weight made of shot, since the weight has to be poured into a narrow glass vessel.
Another use for larger unround shot is split shot. Split shot is lead shot that is cut part-way through the diameter, and has been commonly used as a line weight in angling. Split shot is placed over the line and closed in a crimp using pliers in this application.
[edit] Non Lead Alternatives
There are various places in the world (e.g. Wetlands in Britain) where hunting using lead shot is banned due to the toxic nature of the lead. For these situations, non lead alternatives have been introduced, using materials such as steel, tungsten-nickel-iron, and tungsten-polymer.
