Here is the full list of all 38 Hard West 2 achievements.
Killed 50 Shadow Dancers.
Finish "Frostbitten in Calla Calla" in no more than 10 turns with all objectives completed.
Finish "O'Kane Farm" in no more than 8 turns with all objectives completed.
Completed a mission using only Melee weapons.
Finish "Fooling The Hangman" in no more than 4 turns with all objectives completed.
Finish "Daredevils" in no more than 8 turns with all objectives completed.
Killed 100 Bandits.
Finish "Flynn's Vision" in no more than 10 turns with all objectives completed.
Completed a mission using only Shotguns.
Completed a mission using only Rifles.
Finish "Blasting Out" in no more than 8 turns with all objectives completed.
Completed a mission using only Handguns.
Form sets of Royal Flush with 4 posse at the same time.
Form sets of Straight with 4 posse at the same time.
Form sets of Full House with 4 posse at the same time.
Maxed out loyalty with Flynn.
Maxed out loyalty with Old Man Bill.
Maxed out loyalty with Lazarus.
Maxed out loyalty with Clalish.
Maxed out loyalty with Laughing Deer.
Finish "Riftwalkers" in no more than 10 turns with all objectives completed.
Finish "A Plague Upon This Land" in no more than 12 rounds with all objectives completed.
Finish "3:10 To Heaven" in no more than 1 round with all objectives completed.
Finish "Wanted: Lady Shrike" in no more than 15 turns with all objectives completed.
Finish "The Great Train Heist" in no more than 10 turns with all objectives completed.
Finish "One Last Ride" in no more than 12 rounds with all objectives completed.
Killed 666 enemies.
Killed 60 Hellspawns.
Killed 80 Revenants.
Finished the game on the Easy difficulty.
Finished the game on the Hard difficulty.
Finished the game on the Nightmare+ difficulty.
Completed all world map side objectives in Chapter 1.
Completed all world map side objectives in Chapter 3.
Collected every card in the game.
Visited every location in all Chapters.
Finished the game on the Normal difficulty.
Finished the game on the Nightmare difficulty.