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