Please note that this recording is included purely for the sake of interest; i.e. this is what happens when you position a microphone about fifty feet away from the front of a WWI field gun firing blank charges. It's not meant to be a great recording, but it does show how well the microphone can cope with that sort of abuse.
This is a recording of the six guns firing in order. You can hear how the initial pressure wave diminishes as the distance and angle increases. High level playback will probably harm your speakers - don't blame me!