Here is the full list of all 26 Call of Juarez: Gunslinger achievements worth 400 gamerscore.
Discover a shipwreck in the Missouri swamps.
Kill a shotgunner with a close-range shotgun blast.
Find all Nuggets of Truth in a single mission.
Unlock both exclusive weapons in a single category of skills in Story Mode.
Find and kill Johnny Ringo.
Give it to them straight about your meeting with Pat Garrett.
Kill 5 enemies when falling down through the air.
Unlock a skill.
Find and kill Jim Reed.
Forgive your lifetime nemesis.
Kill your lifetime nemesis honorably in a duel.
Complete the Story on any difficulty.
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.
Complete the duel challenge, winning all duels honorably.
Complete the Story on True West difficulty.
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.
Shoot through a hole to kill an enemy that hides behind a shield.
Reach combo level of 20.
Complete the Story on hard difficulty.
Win a duel honorably in under 0.6s.