Here is the full list of all 26 Call of Juarez: Gunslinger achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Complete the Story on hard difficulty.
Complete the Story on any difficulty.
Forgive your lifetime nemesis.
Find and kill Jim Reed.
Find all Nuggets of Truth in a single mission.
Discover a shipwreck in the Missouri swamps.
Reach combo level of 20.
Find and kill Johnny Ringo.
Shoot through a hole to kill an enemy that hides behind a shield.
Give it to them straight about your meeting with Pat Garrett.
Kill 5 enemies when falling down through the air.
Unlock a skill.
Kill your lifetime nemesis honorably in a duel.
Collect all Nuggets of Truth.
Complete all Arcade missions.
Score the maximum of 3 stars in any Arcade mission.
Get all Arcade Mode stars.
Unlock all skills in Story Mode.
Unlock both exclusive weapons in a single category of skills in Story Mode.
Kill a bird during a winning duel.
Fight in Concentration for 15 minutes.
Shoot a flying stick of dynamite and the one who threw it on a single Concentration.
Complete the Story on True West difficulty.
Complete the duel challenge, winning all duels honorably.
Kill a shotgunner with a close-range shotgun blast.
Win a duel honorably in under 0.6s.