Two bore firearms generally fire spherical balls or slugs made of hardened lead, or in the case of a modern metallic cartridge with either solid brass or bronze projectiles.

[2][3][4] Despite the popularity of the calibre in modern gun lore there is no evidence the 2 bore as named was actually used as a terrestrial and shoulder fired firearm.

The equivalent calibre size equates to various punt guns used for harvesting large number of waterfowls usually mounted in 'punts' or flat bottomed boats for commercial purposes.

The confusion occurs due to Baker's common reference to the projectile fired from the firearm weighing 'half a pound', which would if a round ball equate to a 2 bore by definition.

Among other weapons, I had an extraordinary rifle that carried a half-pound percussion shell—this instrument of torture to the hunter was not sufficiently heavy for the weight of the projectile; it only weighed twenty pounds: thus, with a charge of ten drachms [270 grains] of powder, behind a half-pound shell, the recoil was so terrific, that I spun around like a weathercock in a hurricane.