Boss: Stinger (giant scorpion) | Ecliptic Express Train Walkthrough Resident Evil Zero HD Guide

Use the hunting gun and aim at scorpion's head

You must defeat a giant Stinger scorpion. It is not a hard opponent, but even despite that you should watch yourself as you can quickly lose the health points. Run towards the monster just after the duel starts and aim the hunting gun at its head. It is very important, as the number of damage dealt by this weapon depends on the distance from target. Quickly get away from the opponent after a successful shot (you can retreat traditionally or use the button combination that allows quickly turning by 180 degrees). After he will make a characteristic noise he will attack. Keep attacking him in the described above way and remember that you must reload your weapon after every two shots.

If you are hard pressed, continue only the "regular" shooting

Sooner or later you can be pushed back to the exit door from the bar car. In that case focus only on shooting and don't try to get to the other side of the scorpion. If you're lucky, you will defeat the scorpion using only the hunting gun. If you deplete the ammunition too soon, select the pistol from the inventory. You must also remember about monitoring the health of your character and using spray or herbs whenever the person you control is seriously injured.

Important - If you play this duel as Rebecca, you must be even more careful not to die as she is less resistant than Billy. The duel itself is exactly the same no matter as which of the two you play it.