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