Gold Medal Checklist:
- Loot all safes
- Headshot 5 mounted Lawmen during horseback escape
- Get to Downes Ranch within 1 minute 55 seconds
- Complete with at least 70% accuracy
- Complete the mission without taking any health items
Speak to Bill at camp following the completion of Lenny's mission to follow up on the bank job Karen mentioned back in Chapter 2. Be sure your Dead Eye meter is full and you have means to replenish it, this will be useful in the final parts of this mission.
Follow the gang back to Valentine and leave the horses by the side of the gunsmith. As you approach the bank, you'll have a choice of what act you wish Karen to play, either is fine and result in the same outcome. Once the robbery begins, Arthur will head to the vault with the teller and force him to open the door, beating him three times to speed up the process.
Once in the vault, you have two ways of going about getting the money. The first is to blow them with Dynamite and while this is quick, it will alter the entire town and result in a shootout, ignore this choice. Instead, opt to crack them, you'll need to rotate the [Left Stick] clockwise and anticlockwise to find the numbers. Pay attention to the circle at the bottom of your screen, this indicates how fast and what direction you should rotate while the rumble of the controller indicates if you're close to the number. You'll have around six minutes to loot all of the safes here and you'll need to if you wish to score the Gold Medal.
With the money secure, head outside the bank and follow the others back to your horses when the robbery is discovered. Make your escape by following the rest of the gang, periodically you'll come across mounted Lawmen, hit the Dead Eye button and score at least five headshots for the Gold Medal. Once you've hit the five that you need, consider ignoring the rest of the mounted Lawmen if you're shooting isn't up to scratch, you'll still need to maintain 70% accuracy.
Once you clear the train and lose the Lawmen, the gang will go their separate ways and Arthur needs to make a quick call on the Downes Ranch. Gallop as fast as you can, you need to make the journey within one minute 55 seconds so cut corners where possible to make it in time.