The He-219 was a good looking aircraft, and had an impressive armament, but as stated before, it was grossly under-powered for such a heavy fighter....because they scored a few Mossies on their debut, it didn't make them a Mossie-killer....they were abit quicker than the Bf-110 and Ju-88 that were essentially used as the main radar-capable Luftwaffe Nightfighters, which I guess was why they clobbered a few, and quite possibly the one's they got may have been unarmed Bomber Command Pathfinders and Master-bombers; - Nightfighter Mossies were equipped with tail-warning radar as well as their frontal radar.... - But the He-219's were too few, too slow and too late to compete against an established RAF Nightfighter Force......
Just out of interest, '' shrage Musik ''wasn't a German invention....It was actually traced back to first being used during WWI by the RFC in the Sopwith Dolphins... The first German credited with using it, was Oberleutnant Schonert [...with the umlaut...can't figure-out how to do it on my PC...] who whilst serving with 4/NJG 2, experimented with a Do-17Z-10, using a 7.9mm MG, as a free-moving or a fixed-to-fire-obliquely-upward, weapon. It was not used operationally, but he then proposed a twin-upward-firing 20mm cannon to be tried on the NF version of the Do-217. He got permission to modify 3 of these, which were tested in the Spring of 1943, and Schonert, who was then serving with a Bf-110 unit, scored the first operational victory in May 1943, shooting down an RAF bomber over Berlin....
Over in the Pacific, Commander Yasuna Kozono of the 201st Naval Air Corps was nutting-out how to intercept B-17 B-24 Night-bombers, and his proposal was to have two 20mm cannon fixed to fire up, and two to fire down, both at 30 degree angle....This was first fitted to a Nakajima J1N1-C Gekko [Irving] in the Spring of 1943 [also!].., and the first recorded success was the destruction of two B-24's over Rabaul in May 1943.......