Instrument 004 · ballistics
Fire a tight group of shots — one heading, a hair of spread across the muzzle. The initial group is a short segment of nearly-identical conditions; watch what the traversal does to it. With dispersion on, the segment stretches into a filament and folds across this finite run. Turn dispersion off and the group holds. A focusing geometry can produce a caustic on a dome; this model instead lets you inspect stretch and fold.