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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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Manufacturing
Lead shot was pioneered by William Watts of Bristol who adapted his house on Redcliffe 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.[1]
The process was brought above ground through the building of shot towers.
Due to the act of a falling liquid (in this case molten lead) becoming spherical the falling molten lead becomes spherical as it falls and is then cooled at the bottom of the shaft, most commonly by water.
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).[1]
Hardness of lead shot for shotgun shells is controlled through adding variable amounts of antimony and arsenic, forming lead-antimony alloys.[1]
Sizes
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 economically-viable.
Buckshot
Buckshot is simply lead shot formed to larger diameters. Sizes range in ascending order from size B to Tri-Ball.
Comparison chart
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") |
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 and has a higher density. Completely round shot is not required. Some examples applications are:
- 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.
- Split shot is a larger type of lead shot where each pellet 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.
- The heads of some dead blow hammers are filled with shot to minimize rebound off the struck surface.
- Some scuba diving weight belts are nylon webbing pouches filled with shot: see shot belt.
- It can be used to fill speaker stands for additional acoustic decoupling, as well as stability.
Non lead alternatives
When hunters use lead shot, waterfowl such as ducks can ingest the spent pellets later and get poisoned; predators that eat these birds are also at risk.[2] There are various places in the world (e.g. Wetlands in Britain, North American Wetlands [3] where hunting using lead shot is banned due to the toxic nature of the lead. For these places, nonlead alternatives have been introduced, using materials such as steel, tungsten-nickel-iron, bismuth-tin, and tungsten-polymer.
References
- ^ a b c Guruswamy, Sivaraman (1999). "XIV. Ammunition". Engineering Properties and Applications of Lead Alloys. CRC Press. pp. 569–570. ISBN 9780824782474. http://books.google.de/books?id=TtGmjOv9CUAC.
- ^ Ferreyra, H; Romano, M; Uhart, M (Jul 2009). "Recent and chronic exposure of wild ducks to lead in human-modified wetlands in Santa Fe Province, Argentina". Journal of wildlife diseases 45 (3): 823–7. ISSN 0090-3558. PMID 19617495.
- ^ "Issues in bird hunting: Lead shot vs. nontoxic shot" (pdf). Wisconsin department of natural resources http://dnr.wi.gov/. March 2007. http://dnr.wi.gov/org/land/wildlife/hunt/waterfow/nontoxshot.pdf. Retrieved 2 Feb 2009.
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