Lead shot

Shot is a collective term for small balls or pellets, often made of lead. These were the original projectiles for shotguns and are still fired primarily from shotguns, although shot shells are available in many pistol calibers in a configuration called "bird shot", "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/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 Lead shot was originally made by pouring molten lead through screens into water, forming what was known as "swan shot", and, later, more economically mass-produced at higher quality using a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.

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. 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 while still dropping and thus will retain their spherical form. 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).

The hardness of lead shot is controlled through adding variable amounts of tin, antimony and arsenic, forming alloys. This also affects its melting point. Hardness is also controlled by the rate of cooling that is used in manufacturing lead shot.

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