Back when I lived in Kansas, I lived in a small town called Leonardville. It was fairly close to Fort Riley, a military base that had a specialty in artillery. Whenever they would be practicing, it sounded like thunder across the plains. And we were quite a few miles from the actual artillery range. So, I can only assume what it's like right next to it. So, I can only assume what the sound of a Legion Arquitor Bombard with Morbus Heavy Bombard going off is like. But you'll have to provide your own sound effects if you go order one from Forge World (which you can do now).
From the website:
The Legion Arquitor Pattern Bombard is a heavy artillery platform designed to operate at the forefront of the Legiones Astartes advance. Equipped with a reinforced chassis and brutal short-range firepower, it is called upon to break the most stubborn of fortifications or to annihilate massed enemy infantry and armour.
Available to both Loyalist and Traitor forces, the Legion Arquitor Pattern Bombard can be fielded in units of up to three vehicles. The morbus bombard is able to remove any obstacle to the advance of your Space Marines army in a hail of lethal shells. You can also add even more firepower to your indomitable artillery platform in the form of sponson-mounted heavy bolters or autocannons. If you need to add mobile heavy firepower to your force, the Arquitor Pattern Bombard is ideal.
This highly detailed 45-part resin kit makes one Legion Arquitor Pattern Bombard with Morbus Heavy Bombard.
Rules for fielding the Legion Arquitor Pattern Bombard are available as a free PDF download.