If you are having trouble fighting an endless wave of Riddens while figuring out how to fire the howitzer in the middle, you came to the right place.

This guide will show you how to destroy the mine entrance in Back 4 Blood by loading the 155MM Rounds and firing the howitzer 5 times.

For a short recap, this is the stage after surviving the Gauntlet and finishing the Abandoned stage in Act 1. The Sound of Thunder concludes the story of Back 4 Blood’s first Act.

Act 1 – Sound of Thunder

Sound of Thunder Destroy Mine Entrance

This stage is possibly the shortest out of all the stages in Act 1. There is literally just one objective for the stage and it is to destroy the mine entrance with the howitzer in the middle.

During this stage, once you get down from the saferoom, there will be nonstop waves of Riddens coming for your team. It will never stop until you destroy the mine entrance.

Although, if you deal with the wave of Riddens extremely fast, you will have a few seconds before the next wave arrives. However, playing on Nightmare difficulty will make it hard for you to clear it before the next Riddens arrive.

On top of that, there will be more consistent Tallboy, Reeker, and Stinger spawns. If you are playing with your friends, just have one designated person for doing the howitzer.

How to Load the Howitzer

Sound of Thunder 155mm Rounds

First, you need to grab the 155MM Rounds inside the boxes scattered around the stage. You can find one near the mine entrance on the right, on top of the truck in front of the howitzer, the cabin behind the howitzer, and another one to the left side of the howitzer.

They spawn randomly so some might be missing. Each box may contain more than one 155MM Round so it should be easy. The game will also spawn more than 5 rounds to make it easier.

Once you pick up the 155MM Round, you will not be able to do anything as you are holding it with both hands. Go back to the howitzer and load it by left-clicking while holding the 155MM Round.

For the players not loading the howitzer, they can help by gathering the 155MM Rounds around the area and dropping them near the howitzer. You can do the same by left-clicking them near the howitzer.

Sound of Thunder Loading Rounds

Keep loading them even no one else is loading the rounds. It does not matter if there are a lot of enemies. Trust your teammates to support you so you are progressing.

If not, you might have problems with ammo as the whole stage is literally just loading this howitzer to destroy the mine entrance.

Sound of Thunder Clearing Rounds

After loading, you can click the howitzer to fire the round. You will need to clear the spent round by holding “E” on the howitzer. You have to do this for every round fired so do not forget to clear it before loading the next 155MM Round.

If you plan on just helping the team by killing the Riddens, you can purchase the Ammo Pouch from the shop to get more ammo as an emergency before getting out of the saferoom.

After firing 5 rounds at the mine entrance, it will get destroyed and there will be a Humvee that comes to save the team.

Go to the Humvee and press “E” to enter it. All the players who are alive have to go inside the Humvee to finish the stage. You can enter the Humvee before everyone else so you can use the machinegun inside it to help the others.

This will prompt a cutscene and conclude Act 1 of Back 4 Blood’s campaign.