While I was still with fixed wings, not directly involved, but the night crew (I was day crew) maintaining the Mk-4 gunpods decided to crank off a few 20mm rounds out toward the hills in Chu Lai. You could do that with the ground test gear.
Or rigging up a 19 shot 2.75" rocket pod on a jury-rigged tripod. Ripple fire was impressive, particularly as the blast of each rocket leaving kicked the whole mess up a bit each time. Scared hell out of us that it would go vertical before empty.........
LOL, Goose pimples even.