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Tables of Projectile Shot Sizes

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The tables below present conversions between historically documented shot sizes and modern measurements, for purposes of cross-referencing archaeological specimens with specific types and classes of shot.

Arquebus & Musket Shot / Artillery Shot / Grenades & Bombs

Spanish Arquebus and Musket Shot

During the colonial era, Spanish lead ball shot was normally measured by the weight of the shot, rather than the diameter. For the arquebus (arcabuz) and musket (mosquete) of the 16th and 17th centuries, shot was commonly divided up into that comrising a single lead ball (balas), or shot comprising multiple balls of assorted sizes, ranging from larger postas (buckshot) and smaller perdigones (birdshot). Arquebus shot size was normally said to be ¾ onza to 1 onza. Musket shot size was normally said to be 1½ onzas or greater. Postas were around 1/4 onza, while perdigones were 1/8 onza and smaller.

Two tables are presented below. The first is organized by diameter in millimeters (as commonly measured by archaeologists in the field and lab), and shows equivalent caliber, volume (in cubic cm), and calculated weight in grams, English ounces (@ 28.349375 grams), and Spanish onzas (@ 28.7556 grams). The second is organized by the number of shot per Spanish onza(including ball sizes that were greater than an ounce), and includes equivalent individual shot weights in onzas as well as in English ounces and metric grams, along with conversions to diameter and equivalent caliber based on the density of lead (11.34 grams per cubic centimeter).

For use in Microsoft Excel, the formulae I developed are as follows (with diameters in millimeters and weight in grams, replacing the words below with the appropriate cells):

DIAMETER=20*((WEIGHT/47.35584)^(1/3))

WEIGHT=((DIAMETER/20)^3)* 47.35584

Spanish Shot by Metric Diameter Measurements

Spanish Shot by Number of Shot per Spanish Onza

Spanish Artillery Shot

Spanish artillery were commonly identified by the weight of the iron shot they fired. The chart below derives from a table in an early 19th-century book on artillery. The original table provided shot weights in Spanish libras, and diameter in pulgadas, lineas, and puntos. I have converted these into weights in modern English pounds and metric kilograms, and into diameters measured in total puntos and converted modern metric centimeters. It should be noted that these diameters are for the shot, but artillery bores would have been slightly bigger in order to accommodate the cannonballs within.

Original data above from:

Salas, Ramon de
1833 Prontuario de Artillería, para el servicio de campaña. La Oficina de E. Aguado, Madrid.

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Spanish Grenades and Bombs

The Spanish grenades [granadas] and bombs [bombas] listed below were also made from iron, but were hollow in order to permit explosives inside, with an opening for a fuse [espoleta] to be inserted. Bombas were normally fired using a mortar [mortero], and granadas by a longer mortar called an obus, while hand grenades could either be thrown by hand or fired in clusters from a mortar. The chart below derives from two tables in an early 19th-century book on artillery, and lists the pieces by diameter in Spanish inches [pulgadas], converted by the author from French inches (at a rate of 7 Spanish inches to 6 French inches, more precisely 0.858 French inches per Spanish inch). As in the tables above, the original table also provided shot weights in Spanish libras, and more precise diameters in pulgadas, lineas, and puntos, and I converted these into weights in modern English pounds and metric kilograms, and into diameters measured in total puntos and converted modern metric centimeters.

Original data above from:

Odriozola y Oñativia, José
1827 Compendio de Artillería, o Instruccion sobre Armas y Municiones de Guerra. Imprenta que fue de Fuentenebro, Madrid.

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