Hard West Ultimate Edition

Cañón Calavera is the gun wielded by Joaquim Perez and in order to access it you must first reach the second mission in the ''A Matter of Time'' scenario. During this second mission you must kill Joaquim Perez and complete the additional tasks in the mission. Joaquim is located along the route that you take when completing the additional task. Once you have killed Joaquim you unlock the ability to purchase the Cañón Calavera from the Fate Trader.

Load up a second playthrough of the scenario and then before entering the second mission again, select the option that allows you to ''prepare some more'' and then visit the Fate Trader to purchase the weapon. Start the mission, with the weapon equipped on a character, and reach Joaquim as before and simply land the killing blow on Joaquim with the weapon.