The M3 Combat Shotgun is one of the most useful weapons for attacking stronger monsters in Resident Evil 3 Remake. On this page of our guide you will find information on where to find this firearm in the RE3 and how to unlock the access to this particular weapon (while playing as Jill).
Shotgun is located in the Kite Bros Railway building in the Downtown area. It's an area which you explore just after the prologue of the game. The Kite Bros Railway building is located in the west side of Downtown.
You'll find the shotgun in a locked case in the Subway Office room.
The cabinet doors are locked and secured with a chain and this means you need to get Bolt Cutters first - we described this on a separate page of our guide. As a reminder, you can find them in the Garage. You will get there just after you extinguish the fire in a small alley.
Once you cut the chain, you can open the case and take the weapon. It requires 2 free slots in the inventory.