Before we delve into further detail I would like to take this opportunity to allocate blame where it is due. This all began a couple of years ago when all-round good chap the notorious David Crook gave me a plastic toy mortar. A spring (or rubber band?) loaded device, this lobs round plastic 'shells' to a range of 2-3 feet. So far so good. But hang on (I thought recently) - hadn't I seen pictures of similar mortars mounted on railway cars during the American Civil War? Well yes I had - and so defying all logic and without the aid of a safety net I set out to recreate such a thing.