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