[RyanW]

Originally Posted by maximara

The GURPSwiki has Weapons of GURPS Old West (1830 to 1917) - provided by Curtis Handsaker (Z09SS). Cap and ball would be the rule clear up to the 1880s when the bullet as we know it appeared.

Cartridge rifles were becoming a thing (particularly in the form of lever action repeaters) in the 1860s. Smith & Wesson introduced the cartridge revolver in the 1850s. It would be some time yet before the cartridge designs could compete in power with cap and ball designs.

1873 marked the adoption of breech-loading rifles and cartridge revolvers as standard US Army issue.

The 1880s saw the introduction of "the bullet as we know it" only in the sense of the small caliber, smokeless-powder rifle, in the form of the Lebel Mle 1886. Or the boat-tailed spitzer bullet in the Balle D round for the same rifle in 1889.