There are multiple weapons you find and use in Resident Evil Village. Some of them you naturally discover as you progress through the game, and others you have to make your way through the unbeaten paths to find them. There’s a standard shotgun you receive at the start of the game, the M1897, but you can find the W870 Tac Shotgun later in the game, and it’s easy to miss.
The W870 TAC Shotgun is hidden inside of the Garden. You can find this area to the north of the village, on the pathway to House Beneviento. You have to complete this house before making your way into the garden area. After defeating the second lord, Beneviento, you can explore the garden. Seven ghouls are protecting this location.
After defeating the ghouls, you can freely explore the Garden. You can find the Sun And Moon ball over here, and inside the house is the shotgun. It’s on the right side of the room, on top of a table. When you bring this back to The Duke, he’ll have various upgrades available for you that you can purchase to improve the weapon for the rest of your adventure through Resident Evil Village.