My late father was shot down by a Night Fighter which he beleived was equipped with the "Dancing Music" as he was a rear gunner and never saw the fighter until it opened fire below them, and he then could not depress the guns enough or bring to bear on target. His desciption of 20mm cannon shell fire at night in his words was " like playing tennis with flaming tennis balls" - he was a keen tennis player ! He also beleives only maybe 10 - 15 cannon shells hit the A/C but the damage they did was quickly fatal.
Regards
Mr Mac