This guide might not be the most optimal but this is how I got it on Hard.
Contents
How to Obtain Train Job Achievement (Hard Mode)
All credit goes to Cortia!
Posse
- Deer (loot the locker).
- Flynn (take over the train w/ Gin).
Equipment
- Deer – pair card (I used Jack of Diamonds and Clubs).
- Flynn – atleast a +2 speed card or trinket.
- Gin – Blue Dynamite and remaining + speed trinket & cards.
Looting the Locker
Dismount Deer at the back of the starting carriage next to the ladder to the roof of the carriage behind (should cost 1 AP). Use his Wild Run to kill the nearest sharpshooter on the roof then kill the other sharpshooter. Then have him run straight to the locker and interact/loot it.
Taking Over the Train
Dismount and move Flynn to the 2nd carriage ahead of the starting carriage next to a ricochet target. Shadow Swap Gin then move him near the group of 4 bandits located behind the coal cart (2 AP) then use the Blue Dynamite which should kill 2 sharpshooters. Then with the bravado, have him go straight to the lever to interact.
excellent guide
this is also the easiest way to get “bring a knife to a gunfight” achievement, i think