Ammunition in the game is also limited, so we need to find a place to replenish ammunition. The first method: replace the gun in our hand with the gun on the ground, so that the bullet can move on.
The second method: look around carefully and see if there are any teammates with n or bullets on them. Walk into him and press F to get the bullet.
The third method: check whether there is a box showing bullets in the room or passage, and press the F key for ammunition when it is near.