1. Inspect the photographs for details of the gunslingers' locations
Open your satchel and inspect the backsides of the photographs of Black Belle, Billy Midnight, Falco Hernandez, and Emmet Granger. Once you do this, the last known gunslingers' positions will be marked on your map.
2. Emmet Granger
You'll find him on his farm east of the Flatneck Station. He will be alone and you can talk to him.
He promises to tell you about his past if you clean up his pigsty.
Emmet Granger promises to help with Levin's Boy Galloway biography, if his pigsty is cleaned up first.
2.1. Clear out the manure
Take the pitchfork that stands next to the fence. Use it to collect the droppings lying in the pen and toss them on the wheelbarrow.
When you do this, Arthur will take the content of the wheelbarrows to the nearby manure depot and ask Granger to fulfill his promise. However, he won't want to tell Arthur any more than he did.
2.2. Place dynamite on the manure store
Angry Arthur will take the dynamite off the table. You have to place dynamite on the manure store.
As a result of the explosion, Granger will be showered with a rain of manure, which will make him very angry and lead to a duel.
2.3. Defeat Emmet Granger in the duel
After his farm is covered in pig manure, retired gunslinger Emmet Granger fights one last duel.
Kill him before he kills you.
2.4. Take a closeup photo of Emmet Granger
When you defeat Granger, equip the camera and take a picture of him. The photo must show his head.
You can take his gun from his corpse - Granger's Revolver.
3. Flaco Hernández
Falco Hernandez is located in the camp near the frozen Cairn Lake. He is in his cabin, and there are some of his men outside.
3.1. Search the camp for Flaco Hernández
In order to draw him out of his cabin, you have to kill or threaten his men outside. If you threaten them, they'll run away when you kill Flaco.
3.1.1. (Optional) Defeat the Del Lobo
If you choose a violent solution, you'll have to kill all the gang members.
3.1.2. Go to the shack / Call Flaco Hernández
Approach Flaco's cabin, holster your weapons, and call him out.
After a while, Flaco will go outside, but he won't want to talk to you. Get ready for a duel.
3.1.3. Defeat Flaco Hernández in the duel
Drawn out of his cabin, the outlaw Fluco Hernández fights a duel.
3.1.4. Take a closeup photo of Flaco Hernández
When you defeat Flaco, equip the camera and take a picture of him.
Next to his corpse, you'll find his gun - Flaco's Revolver.
4. Billy Midnight
To meet this gunslinger you need to go to Rhodes and talk to a clerk at the station. He will tell you that Billy should be on the train that is about to arrive at the station.
4.1. Wait for the train to stop / Search the train for Billy Midnight
Get on the train and go to the restaurant car. Billy will be standing by the bar, talk to him.
Apparently, Billy's got something on his conscience, he's gonna get scared of you and start running.
4.2. Chase Billy Midnight
Fearing his past has finally caught up to him, Billy Midnight flees to the roof of a moving train where he meets his fate.
Billy's gonna run towards the front of the train and then he's gonna go up on the roof. Soon, however, he will stop because he will have nowhere to run.
When you get close to him, you will have to duel him. If you don't get close to him, Billy will kill himself after a while and all you have to do is take a picture of him.
4.3. Take a closeup photo of Billy Midnight
Next to the body you'll find his gun - Midnight's Pistol.
5. Black Belle
Black Belle resides in a house in Bluewater Marsh north of Saint Denis. Approach the house in the swamp and you'll be able to meet her.
She is expecting a bounty hunters visit and if you want her to give you information you need, then you will have to help her get rid of them. Black Belle will also inform you that she has placed explosives in the area around the cabin and two detonators are right next to you.
5.1. Deal with the Bounty Hunters
You will have to eliminate a dozen or so bounty hunters who will attack from different sides. You can use the explosives left by Belle, but most of them will still have to be shot.
The biggest threat will be a wagon with a mounted machine gun.
Once you've eliminated all enemies, Belle will tell you a little bit about the past as promised.
She won't have any problems with you taking a picture of her.
5.2. Take a closeup photo of Black Belle
After defending her hideout in Bluewater Marsh, the gunslinger known as Black Belle poses for a photograph for Levin's biography of Boy Calloway.
When you take a picture of her, Belle will say goodbye and she goes her way.
6. Part II
You've dealt with all the gunslingers, go to Calloway and Levin with the findings.
7. Look for Calloway on the riverboat in Saint Denis (Part III)
Calloway and Levin are in Saint Denis, go there with the findings.
Go to the port in Saint Denis and ask the ship's guard about Calloway.
He will lead you to the cabin occupied by Calloway and Levin.
Calloway does not want to take credit for the tracking down of his old rivals, and wants to prove himself against ex-gunslinger new State Marshal Slim Grunt.
8. Locate and capture Slim Grant in Annesburg (Part IV)
Calloway wants to settle an old score with State Marshall, Slim Grant.
Go to the sheriff's office in Annesburg.
Slim Grant is not there and his deputy will tell you that a few days ago he went west to catch some criminals.
9. Locate Slim Grant at the outlaw camp / Capture Slim Grant alive
Go to the place marked on the map. Slim Grant has been captured by bandits and is tied to a tree.
Shoot the bandits and untie Slim Grant from the tree. Arthur will keep his hands and legs tied and load him on his horse.
10. Deliver Slim Grant to the drop off point / Place Slim Grant by Levin
Take Slim Grant to the designated location, take him off the horse and put him on the ground next to Levin.
Slim Grant refuses to fight Calloway and will want to leave but Calloway will shoot him in the back and kill him.
Calloway will go crazy and want to duel with Arthur. You have no choice but to face him.
11. Deal with Calloway
Standard duel, be faster than Calloway.
When you kill him, you can take Calloway's Revolver and Levin will get a very good ending for his book.