These muzzle loading rifles came in a large variety of calibres, the most common calibres for medium thin skinned plains and deer sized game were , , , and 12 bore (18.5 mm or .729 in). For larger thick skinned type game 10 bore (19.7 mm or .775 in), 8 bore (21.2 mm or .835 in) and 4 bore (26.7 mm or 1.05 in) were used, the last being a specialist elephant hunting calibre. Whilst most of these calibres could be purchased with rifling, the giant 4 bore and the less common 6 bore were rarely rifled, as the increased friction from the rifling caused excessive recoil.