Taking the Sting Out, your first Boss Fight.
Stinger, Giant Scorpion.
After you leave your Partner in the Kitchen and transported the Conductor Key via Dumbwaiter, make your way to the Conductor's Room.
On the wall next to the door, you should see a flickering red Switch. Press it and reveal a ladder leading to the Train Bar (2ndF).
After a Scene run down the Corridor and through the door. Make your way to the Cabin and pick up the Hunting Rifle and Ammo.
After you picked up all the items make your way back to the Train Bar to face Stinger.
The fight is very easy (on easy
)... it takes a few shits from the Hunting Rifle and a few shots from the Handgun to finish him off.
Make sure you stay away from him after the last shot!!!!!!! He will Attack one last time before he dies.
All Credit for the Video goes to Andreas Contreras.
Hope it helps