Gun

To start the Bounty Hunter side mission, all you need to do is locate a Wanted Poster and press to examine it. These can be found in either Dodge City or Empire City and in certain places outside of the cities. Then all you need to do is track down the wanted people and either kill them or capture them depending upon the mission. There are twelve missions in total and the achievement will unlock once you have completed them all.

Each one of the six different types of side missions in the game is pretty straightforward but can still be somewhat challenging due to some of the time constraints placed on some of them. Here are the various types of side missions and how to get their respective achievements:

• Texas Hold ‘Em
  • These can be found in Dodge City and Empire City and are pretty standard editions of Texas Hold ‘Em. There are 6 missions in total. I personally found this very frustrating as it may seem rigged for your opponents to win. However, here are some tips that I found to be pretty helpful:
    • Hold onto face cards when you can get them.
    • Cheat when necessary.
    • Go all in to scare the AI. This can be pretty hit or miss, so read below for another tactic.
    • Raise the bet rather than go all in. The AI seems to fold more if you are really ballsy with raising the stakes.
• Pony Express
  • These missions are found in various spots around the map and task you with delivering an item to a specific destination in a pretty short time limit. Some of the missions have multiple parts of this. There are 10 of these in total. For me, I had to do all 10 of them for it to count toward the 100% needed for the last weapon.
• Keep the Peace
  • Theses side missions are located in Dodge City and Empire City. They are shown on the map by the Sheriff and the U.S. Marshall stars in their respective cities. They task you with completing various tasks around the towns such as rescuing hostages, returning explosive barrels, clearing out gang shootouts, etc. They are very easy to complete and are actually fun.
• Horse Challenges
  • These are very quick and easy missions that involve you assisting the rancher that you meet early on in the story.
• Hunting
  • These missions are located at the Indian Hunter blip on the map. He tasks you with killing various rare animals around the map. You can use your guns to complete the mission despite it instructing you to use a bow. Take note that you must sneak using to get close to the animal before you use your weapon. You can cheese this using the method described in "Insane Difficulty Completed".
• Bounty Hunting
  • These missions are indicated by wanted posters in Dodge City and Empire City and sometimes the surrounding areas of each town. They are pretty easy and fun missions that task you with killing or subduing a wanted fugitive.

Note: You can cheese all of these achievements using the steps described in "Insane Difficulty Completed". This will also count toward the 100% stat. As stated above, for me the only one I needed to do every single mission for to count for the completion % was Pony Express.

Regardless, you will unlock all of these achievements once you have completed the final mission of that respective side activity.