I must say I have never seen the chin guns fire in either movies or real footage...I know that prior to them being fitted the Luftwaffe had identified the advantage of a frontal attack...and that that tactic fell by the way side after the installation of the forward guns...so did they need so much ammo (or any) once the Luftwaffe changed their tactics? A coupe of black painted broom sticks may have sufficed...
FalkeEins - the Luftwaffe blog: Ju 88 G of IV./ NJG 3- Schräge Musik, Unternehmen Gisela 03 March 1945, Ebay find # 92
Schräge Musik, which may also be spelled Schraege Musik, was a common name for the fitting of an upward-firing autocannon or machine gun, to an interceptor aircraft, such as a night fighter. The term was introduced by the German Luftwaffe during World War II. "Schräge Musik" was previously a German colloquialism, meaning music that featured an unusual tuning and/or time signature. By itself, the word Schräge has often been translated as "slanting" or "oblique", although it may instead be rendered into English as "weird" or "strange". The first such systems were been devised World War I. They were also developed and used by the Japanese military during World War II. Like the Luftwaffe, the Imperial Japanese Navy Air Service (IJNAS) and Imperial Japanese Army Air Service (IJAAS) fitted such weapons to twin-engined night fighters. Both the Luftwaffe and IJNAS had their first victories with upward-firing autocannons in May 1943. Night fighters used them to approach and attack Allied bombers from below, outside the bomber crew's field of view and/or defensive fire. Many of the commonly-used Allied night bomber aircraft of that era (such as the Avro Lancaster) lacked ventral turrets (such as ball turrets), making them vulnerable to approaches and attacks from below. In the initial stages of its use operational use by German air crews, from mid-1943 to early 1944, many attacks using Schräge Musik achieved complete surprise while destroying bombers. The Allied bomber crews that survived such attacks, during this period, often believed that damage and casualties had been caused by ground-based anti-aircraft artillery (AA or AAA),[1] rather than fighters. The complete technical details and tactical usage of German Schräge Musik systems were not fully understood by Allied air forces until after the end of the war in Europe. Typical installations Dornier Do 217N: 4 × 20 mm MG 151/20 Focke-Wulf Fw 189: 1 × 20 mm MG151/20 (used mainly on Eastern Front) Heinkel He 219: 2 × 30 mm MK 108 Junkers Ju 88C/G: 2 × 20 mm MG 151/20 Junkers Ju 388J: 2 × 30 mm MK 108 Messerschmitt Bf 110G-4: 2 × 20 mm MG FF/M Messerschmitt Me 262B-2: 2 × 30 mm MK 108 (proposal only, B-2 version never produced) Focke-Wulf Ta 154: 2 × 30 mm MK 108 The cause of losses... killed novice and expert crews impartially. This result contradicted the official dogma... I blame the ORS and I blame myself in particular, for not taking this result seriously enough... If we had taken the evidence more seriously, we might have discovered Schräge Musik in time to respond with effective countermeasures. — Freeman Dyson[
Simple and deadly. often the major problem was that the falling plane hit yours....hitting the fuel tank made the enemy plane fall like a stone.
Walter Nowotny, top scorer ace who burnt when his Me-262 was shot down. Victories : 258 Awards : Ehrenpokal (14 July 1942) Deutsches Kreuz in Gold (21 August 1942) Ritterkreuz (4 September 1942) Eichenlaub (4 September 1943) Schwertern (22 September 1943) Brillanten (19 October 1943) Units : JG 54, JG 101, Kdo Nowotny