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