Achievements:
Austin Overpowered
Complete Twin Rocks, Pike's Basin, and Gaptooth Breach Hideouts in Single Player.
Bearly Legal
Kill and skin 18 grizzly bears.
Buckin' Awesome
Break the Kentucky Saddler, the American Standardbred, and the Hungarian Half-bred.
Bullseye
Get 250 headshots in any game mode.
Clemency Pays
Capture a bounty alive.
Evil Spirits
Complete Tumbeweed and Tesoro Azul Hideouts in Single Player.
Exquisite Taste
Purchase a rare weapon from a gunsmith.
Fightin' Around the World
Knock someone out in melee in every saloon in the game in Single Player.
Friends in High Places
Use a Pardon Letter with more than $5,000 Bounty in Single Player.
Frontiersman
Obtain Legendary rank in any Single Player Ambient Challenge.
Go Team
Be on the winning team for four consecutive victories in any team based game in public matches
Gold Medal
Earn a Gold Medal Rank for a combat mission in Single Player.
Have Gun Will Travel
Complete all Hideouts in a single public Free Roam session
He Cleans Up Well!
Obtain the Elegant Suit.
High Roller
Win over 2,000 chips in a hand of Poker or Blackjack.
Hit the Trail
Get from Blackwater to Escalera before sundown in a public Free Roam session
How the West Was Won
Reach the top rank for multiplayer experience.
In a Hail of Bullets
Kill 500 enemies with any pistol or revolver in any game mode.
Instinto Asesino
Complete Fort Mercer and Nosalida Hideouts in Single Player.
Long Arm of Marston
Kill 500 enemies with any rifle, repeater, or shotgun in any game mode.
Man of Honor / Chivalry's Dead
Attain highest Fame rank and either highest Honor rank or lowest Honor rank.
More than a Fistful
Earn $10,000 in Single Player.
Most Wanted
Maintain a max wanted level for 10 minutes and escape alive in a public Free Roam session.
Mowing Them Down
Kill 500 enemies with a mounted weapon in any game mode.
No Dice
Complete a game of Liar's Dice without losing a single die.
People are Still Strange
Complete 15 tasks for Strangers.
Posse Up!
Create a posse and get the maximum number of members
Red Dead Rockstar
Kill a Rockstar or someone with this achievement in a public multiplayer match.
Redeemed
Attain 100% in the Single Player Game Completion stat.
Slow on the Draw
Get 10 assists in a single Hideout in a public Free Roam session
Strange Things are Afoot
Complete a task for a Stranger.
The Gunslinger
Get a headshot while in Expert Mode in Single Player.
The Quick and everyone else…
Be the top scoring player in any three consecutive FFA games in public matches
Unnatural Selection
Kill one of every animal species in the game in any game mode.
What About Hand Grenades?
Get a ringer in a game of Horseshoes in any game mode.
van IGN.com