Here is the full list of all 21 Western 1849 Reloaded achievements.
Perform 500 perfect reloads
Complete very hard difficulty
Fire 5000 bullets
Kill 2000 Bandits
Knock down 250 hats from bandits
Kill 100 bandits using dynamite
Complete hard difficulty
Perform 500 head shots
Upgrade your equipment 3 times
Shoot 50 canns
Perform a 15 kill streak
Complete medium difficulty
Perform 50 headshots in one game
Have 2 items equipped in the backpack
Perform 50 Perfect Reloads in one game
Fire 100 bullets in one game
Complete 3 waves in a row without losing any health
Complete easy difficulty
Kill 6 bandits with one clip
Kill 25 bandits in Rage Mode
Complete insane difficulty