Definition
A chain of shells is a series of shells of the same calibre linked by quick match, so that one ignition fires them one after another at a regular interval. The mortars are lined up in a rack and the fuse runs from one to the next through a delay of a few tenths of a second to two seconds. It is also called chain fusing or a cadence. A typical chain holds 5 to 25 shells of 50 to 100 mm; it produces a column or a line of close-set bursts that builds in intensity, an effect widely used in finales. It saves firing cues but fixes the rhythm: once started, a chain neither stops nor corrects itself, which demands careful fusing and firing from a clear site.
In practice, for the display company
A chain is planned as a single piece but stocked and declared as several shells: PyroDesk deducts each shell from stock and sums their explosive content while assigning only one cue in the firing plan. PyroSimulator replays the chosen cadence so you can fit the chain to the music and check it does not overlap the next bouquet.