MK 108 cannon: Difference between revisions

MK 112
MK 112
Production history
Designer	Rheinmetall-Borsig
No. built	15 (prototypes)
Variants	2
Specifications
Mass	300 kilograms (660 lb); 275 kilograms (606 lb) (improved version)
Length	2,012 millimetres (79.2 in)
Cartridge	55×175RBmm (1485 g)
Caliber	55 mm
Action	API blowback
Rate of fire	300 rounds/min
Muzzle velocity	594 m/s (1,950 ft/s)

MK 108
MK 108
	Two MK 108 autocannon, RAF Museum Cosford (2010)
Type	Autocannon
Place of origin	Nazi Germany
Service history
In service	1943–1945
Used by	Nazi Germany
Wars	World War II
Production history
Designer	Rheinmetall-Borsig
Designed	1940
Manufacturer	Rheinmetall-Borsig
Produced	1943–1945
Specifications
Mass	58 kilograms (128 lb)
Length	1,057 millimetres (41.6 in)
Barrel length	580 millimetres (23 in)
Cartridge	30×90mmRB (330g) steel casing
Caliber	30 mm
Action	API blowback
Rate of fire	650 rounds/min; MK 108A: 850 rounds/min[citation needed]
Muzzle velocity	540 m/s (1,770 ft/s)

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The MK 108 (German: Maschinenkanone—"machine cannon") is a 30 mm caliber autocannon manufactured in Germany during World War II by Rheinmetall‑Borsig for use in aircraft.^[1]

The cannon saw widespread use as an anti-bomber weapon during the second half of the war, first seen in 1943 in the Bf 110G-2 bomber destroyers and Bf 109G-6/U4.^[1]

Four MK 108s formed the main armament of the Me 262 the next year.^[2] It could be found on some versions or optional mountings on practically every other German fighter of the era.^{[citation needed]}

Development

The weapon was developed as a private venture by the company in 1940 and was submitted to the Reichsluftfahrtministerium (RLM—Reich Aviation Ministry) in response to a 1942 requirement for a heavy aircraft weapon for use against the Allied heavy bombers appearing over German-controlled regions by then. Testing verified that the autocannon was well suited to this role, requiring on average just four hits with its 85g RDX-load (in a 330g shell) and a resulting strongly brisant high-explosive ammunition, to bring down a heavy bomber such as a B-17 Flying Fortress or B-24 Liberator, and just a single "shattering" hit to down a fighter. In comparison, the otherwise excellent 20 mm MG 151/20 (18g of HE in a 92g shell) required about 15 to 20 hits to down a B-17.

The MK 108 was quickly ordered into production and was installed in a variety of Luftwaffe fighter aircraft. It saw first operational service in summer 1943 with the Bf 110G-2 bomber destroyers and in the Bf 109G-6/U4.^[3]

Design details

Ammunition

Side view, MK 108

The cannon used specially-developed 30×90RB mm ammunition—30 mm calibre, 90 mm case length, rebated/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including practice, armor-piercing, high-explosive and incendiary. In operation, however, two major ammunition types were used: mine shell and high-explosive incendiary. The mine shell was made by drawn steel (the same way brass cartridge-cases are made) instead of being forged and machined as was the usual practice for cannon shells.^[4]

This resulted in a shell with a thin but strong wall, which hence had a much larger cavity in which to pack a much larger explosive or incendiary charge than was otherwise possible.^{[citation needed]}

Construction

The cannon proved to be relatively light, effective, reliable, compact and easy to manufacture due to its simple construction—80% of the weapon was made from stamped parts, and the number of moving parts was kept to a minimum by using advanced primer ignition blowback (APIB) operation. The simplicity of construction allowed inexperienced workers to make the parts (mostly women).^[4]

The MK 108 was optimized for a high rate of fire at the expense of ballistic performance.^{[citation needed]}

It was easy to maintain, and its compact size, low weight and electrical priming made it ideal for aircraft installation. ^{[citation needed]}

The cannon's distinctive heavy pounding sound and high rate of fire gave it the nickname "pneumatic hammer"^[1] amongst Allied aircrews, who feared its destructive power.

Mechanism

Normally, gas-operated or recoil-operated mechanisms are used in automatic weapons of rifle calibre and larger because the chamber pressure in such weapons is very high. Therefore, if a simple blowback system (where there is no positive lock between the bolt and barrel) is used, the bolt may recoil and open the breech while the chamber pressure is still high, causing damage to the weapon and split cases (see blowback article for more information). To avoid this, simple blowback guns have to use low-powered cartridges or a very heavy bolt.^{[citation needed]}

In an Advanced Primer Ignition Blowback design such as the MK 108, the forward motion of the bolt is used instead of a locking mechanism to prevent this premature opening. When the 108 is ready to fire, the bolt and main spring are held back at the rear of the gun, the spring under considerable tension. When the trigger is squeezed, they are released and shoot forward at a high speed. The bolt picks up a cartridge and chambers it, but instead of coming to rest against the breech face, it follows the case a small distance into the chamber—which is of course made specially longer in these guns to accommodate this manoeuvre.^[5] Also a cartridge case with a rebated rim is used, so that the extractor claw can hook over the rim and still fit within the chamber.^[6]

Primer ignition is timed so that the bolt is still moving forward when the propellant is ignited. The expanding gases from the fired round stop the forward motion of the bolt, then reverse its motion. The key characteristic of the APIB system is that, because the resistance due to the weight of the bolt and the mainspring are supplemented by the bolt's considerable forward momentum, the propellant gases are contained in the barrel for critical microseconds, and the projectile will have had time to leave the muzzle, allowing the gas to escape forward and reducing the chamber pressure to a safe level before the bolt and cartridge case emerge from the opposite end.^[6] Once they emerge the weapon cycles like other automatic guns, with one significant exception: instead of simply ejecting the spent cartridge case, the 108 reinserts it into the empty link in the ammunition belt. The heavy bolt continues backwards, compressing the main spring. When the spring is fully compressed it begins to expand forwards again, reversing the motion of the bolt and recommencing the cycle. This sequence is repeated until the trigger is released or the ammunition is exhausted.^[5]

The APIB design makes practical the use of far more powerful ammunition than with simple blowback operation, but the length and the speed of the bolt's movement within the chamber are limited by the stresses placed on the case by the sliding motion, which takes place under high gas pressure. To keep these within limits either the bolt must be heavy to absorb the pressure, or the barrel must be short to limit the duration of high pressure within the barrel.^[5] The operational tradeoff is that a heavy bolt reduces the rate of fire while a short barrel reduces ballistic performance.^{[citation needed]} The designers of the MK 108 opted for a high rate of fire and thus used a relatively light bolt, accepting reduced ballistic performance due to the corresponding necessity of a short barrel. As a result, the MK 108 had a muzzle velocity of only 540 m/s,^[1] compared to the approx. 800 m/s for the MG 151/20.^[7]

Another significant feature is that, in the APIB system the cycle starts with the bolt open, which prevents an autocannon using the APIB principle from being accurately synchronized with an aircraft's propeller.^[6]

MK 108 bolt cycle

MK 108 feed cycle

Operational usage

The MK 108 saw widespread use among fighters tasked with shooting down enemy bombers. Some of the aircraft deploying, or intended to be armed with, the MK 108 were Messerschmitt Bf 109,^[8] Messerschmitt Bf 110,^[9] Messerschmitt Me 163,^[10] Messerschmitt Me 262,^[11] Focke-Wulf Fw 190,^[12] Focke-Wulf Ta 152,^[12] Focke-Wulf Ta 154,^[13] Heinkel He 162,^[14] Heinkel He 219,^[13] Horten Ho 229^[15] and Junkers Ju 388.^[16]

The MK 108 was also fitted to night fighters in an unusual installation, called "Schräge Musik" (literally "awkward music" or "slanted music"). In this configuration, the cannons were mounted in the fuselage, aiming upwards and slightly forwards at an oblique (18 to 30 degree) angle, depending on fitment and aircraft. This allowed the night fighter to attack bombers, often undetected, by approaching from underneath the enemy aircraft - many British heavy bombers had neither weapons on the ventral fuselage nor windows for vision. This installation was so effective that discovery and news of its adoption was much slower than usual in reaching British night-bombing forces, as there were rarely any survivors from the attacks to report the new threat. This system was fitted to some versions of the He 219 Uhu, late-model Bf 110 night fighters, Junkers Ju 88 & 388 and the Dornier Do 217N model. It was also fitted more rarely to the (prototype) Focke-Wulf Ta 154 and Fw 189 along with the planned, two-seat Me 262B-2 jet night-fighter. In the latter case this produced a jet fighter with six MK108 cannons - with the fitment of the projected mass-produced, mid-VHF band FuG 218 radar.

Related designs

The MK 108 mechanism was scaled up in the MK 112 cannon, using a 55×175RB cartridge. The MK 112 was intended to be fitted in pairs in the nose of Me 262 fighters, with 25 rounds per gun, and also in the nose of later models of the Arado Ar 234 for night fighter duty. Underwing mounts for the twin-engined, high-speed Dornier Do 335 heavy fighter were in development as well. The gun was not finished in time to see operations in World War II.^[17] Only 15 prototypes were built; of these 10 were delivered for tests and 5 were kept at the factory for improvements based on expected feedback. Of the ten guns delivered for tests, seven were of an early model, weighing 300 kg (660 lb), and three were lighter at 275 kg (606 lb) — these were both significantly lighter than the slightly smaller, 50-mm calibre, 21-round armed Bordkanone-series BK 5 cannon, itself weighing some 540 kg (1,190 lb). The MK 112's projectile was supposed to weigh 1.5 kg (3.3 lb); of these, 420 g (15 oz) were reserved for the explosive.^[18] The US captured some of these prototypes and knowledge gleaned from them was incorporated into the experimental US 57 mm T78 autocannon, but this did not see production either.^[17]

References

^ ^a ^b ^c ^d Lepage, Jean-Denis G. G. (23 March 2009). Aircraft of the Luftwaffe, 1935-1945: An Illustrated Guide. McFarland. ISBN 978-0-7864-5280-4.
^ Forsyth, Robert (19 January 2023). Me 262: Northwest Europe 1944–45. Bloomsbury Publishing. ISBN 978-1-4728-5053-9.
^ Messerschmitt Bf 109 F, G, & K Series by Jochen Prien, Peter Rodeike page 108.
^ ^a ^b Heath, Tim (21 September 2022). In Furious Skies: Flying with Hitler's Luftwaffe in the Second World War. Pen and Sword History. ISBN 978-1-5267-8524-4.
^ ^a ^b ^c Armor. U.S. Armor Association. 1994.
^ ^a ^b ^c Williams, Anthony G. (2 August 2022). Autocannon: A History of Automatic Cannon and Ammunition. The Crowood Press. ISBN 978-1-78500-921-1.
^ Bernstein, Jonathan (28 October 2021). P-47 Thunderbolt vs German Flak Defenses: Western Europe 1943–45. Bloomsbury Publishing. ISBN 978-1-4728-4630-3.
^ Jackson, Robert (30 July 2018). Messerschmitt Bf 109. Pen and Sword. ISBN 978-1-5267-1055-0.
^ III, Marshall Michel (23 January 2020). Schweinfurt–Regensburg 1943: Eighth Air Force's costly early daylight battles. Bloomsbury Publishing. ISBN 978-1-4728-3868-1.
^ Graff, Cory (1 November 2014). Flying Warbirds: An Illustrated Profile of the Flying Heritage Collection's Rare WWII-Era Aircraft. Zenith Press. ISBN 978-1-62788-495-2.
^ Oehler, Robert; Green, Brett (20 April 2012). Modelling the Messerschmitt Me 262. Bloomsbury Publishing. ISBN 978-1-78096-686-1.
^ ^a ^b Graf, Mantelli-Brown- Kittel- (28 February 2017). The Focke-Wulf Fw 190 (in Italian). Edizioni R.E.I. ISBN 978-2-37297-325-0.
^ ^a ^b Stemp, P. D. (19 April 2013). Kites, Birds & Stuff - Aircraft of GERMANY - E to H. Lulu.com. ISBN 978-1-291-29268-8.
^ Dorr, Robert F. (15 November 2013). Fighting Hitler's Jets: The Extraordinary Story of the American Airmen Who Beat the Luftwaffe and Defeated Nazi Germany. Voyageur Press. ISBN 978-0-7603-4398-2.
^ Metzmacher, Andreas (2 December 2021). Gotha Aircraft: From the London Bomber to the Flying Wing Jet Fighter. Fonthill Media.
^ Forsyth, Robert (23 June 2022). Junkers Ju 188 Units of World War 2. Bloomsbury Publishing. ISBN 978-1-4728-3636-6.
^ ^a ^b Anthony G. Williams (2002). Rapid Fire: The Development of Automatic Cannon, Heavy Machine-Guns and Their Ammunition for Armies, Navies and Air Forces. Airlife. p. 169. ISBN 978-1-84037-435-3.
^ George Chinn 1951, The Machine Gun: Development During World War II and Korean Conflict by the United States and their Allies of Full Automatic Machine Gun Systems and High Rate of Fire Power Driven Cannon, Volume III, Parts VIII and IX., p. 627

External links

MK 108 ammunition types
World War 2 Fighter gun effectiveness comparison Archived 30 October 2017 at the Wayback Machine
factsheet from the National Museum of the United States Air Force, Dayton, Ohio
German language page on the MK 108 autocannon

[:0-1] Lepage, Jean-Denis G. G. (23 March 2009). Aircraft of the Luftwaffe, 1935-1945: An Illustrated Guide. McFarland. ISBN 978-0-7864-5280-4.

[2] Forsyth, Robert (19 January 2023). Me 262: Northwest Europe 1944–45. Bloomsbury Publishing. ISBN 978-1-4728-5053-9.

[3] Messerschmitt Bf 109 F, G, & K Series by Jochen Prien, Peter Rodeike page 108.

[:1-4] Heath, Tim (21 September 2022). In Furious Skies: Flying with Hitler's Luftwaffe in the Second World War. Pen and Sword History. ISBN 978-1-5267-8524-4.

[:3-5] Armor. U.S. Armor Association. 1994.

[:2-6] Williams, Anthony G. (2 August 2022). Autocannon: A History of Automatic Cannon and Ammunition. The Crowood Press. ISBN 978-1-78500-921-1.

[7] Bernstein, Jonathan (28 October 2021). P-47 Thunderbolt vs German Flak Defenses: Western Europe 1943–45. Bloomsbury Publishing. ISBN 978-1-4728-4630-3.

[8] Jackson, Robert (30 July 2018). Messerschmitt Bf 109. Pen and Sword. ISBN 978-1-5267-1055-0.

[9] III, Marshall Michel (23 January 2020). Schweinfurt–Regensburg 1943: Eighth Air Force's costly early daylight battles. Bloomsbury Publishing. ISBN 978-1-4728-3868-1.

[10] Graff, Cory (1 November 2014). Flying Warbirds: An Illustrated Profile of the Flying Heritage Collection's Rare WWII-Era Aircraft. Zenith Press. ISBN 978-1-62788-495-2.

[11] Oehler, Robert; Green, Brett (20 April 2012). Modelling the Messerschmitt Me 262. Bloomsbury Publishing. ISBN 978-1-78096-686-1.

[:4-12] Graf, Mantelli-Brown- Kittel- (28 February 2017). The Focke-Wulf Fw 190 (in Italian). Edizioni R.E.I. ISBN 978-2-37297-325-0.

[:5-13] Stemp, P. D. (19 April 2013). Kites, Birds & Stuff - Aircraft of GERMANY - E to H. Lulu.com. ISBN 978-1-291-29268-8.

[14] Dorr, Robert F. (15 November 2013). Fighting Hitler's Jets: The Extraordinary Story of the American Airmen Who Beat the Luftwaffe and Defeated Nazi Germany. Voyageur Press. ISBN 978-0-7603-4398-2.

[15] Metzmacher, Andreas (2 December 2021). Gotha Aircraft: From the London Bomber to the Flying Wing Jet Fighter. Fonthill Media.

[16] Forsyth, Robert (23 June 2022). Junkers Ju 188 Units of World War 2. Bloomsbury Publishing. ISBN 978-1-4728-3636-6.

[Williams2002-17] Anthony G. Williams (2002). Rapid Fire: The Development of Automatic Cannon, Heavy Machine-Guns and Their Ammunition for Armies, Navies and Air Forces. Airlife. p. 169. ISBN 978-1-84037-435-3.

[18] George Chinn 1951, The Machine Gun: Development During World War II and Korean Conflict by the United States and their Allies of Full Automatic Machine Gun Systems and High Rate of Fire Power Driven Cannon, Volume III, Parts VIII and IX., p. 627

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@@ Line 1: / Line 1: @@
+{{Short description|WWII-era German 30mm aircraft autocannon}}
 {{Infobox weapon
 |name=MK 108
@@ Line 32: / Line 33: @@
 |crew=
 <!-- Ranged weapon specifications -->
-|cartridge=30×90RB (330g) steel casing
+|cartridge=30×90mmRB (330g) steel casing
 |caliber=30 mm
-|action=[[API Blowback]]
+|action=[[API blowback]]
 |rate=650 rounds/min<br> MK 108A: 850 rounds/min{{cn|date=September 2022|reason=unreliable source removed}}
 |velocity=540 m/s (1,770 ft/s)
@@ Line 71: / Line 72: @@
 }}
-The '''MK 108''' (German: ''Maschinenkanone''—"machine cannon") was a [[30 mm caliber]] [[autocannon]] manufactured in [[Nazi Germany|Germany]] during [[World War II]] by [[Rheinmetall]]‑[[August Borsig|Borsig]] for use in [[aircraft]].<ref name=":0">{{Cite book |last=Lepage |first=Jean-Denis G. G. |url=https://books.google.com/books?id=hdQBTcscxyQC&newbks=0&printsec=frontcover&pg=PA54&dq=MK+108++Rheinmetall&hl=en |title=Aircraft of the Luftwaffe, 1935-1945: An Illustrated Guide |date=2009-03-23 |publisher=McFarland |isbn=978-0-7864-5280-4 |language=en}}</ref>
+The '''MK 108''' (German: ''Maschinenkanone''—"machine cannon") is a [[30 mm caliber]] [[autocannon]] manufactured in [[Nazi Germany|Germany]] during [[World War II]] by [[Rheinmetall]]‑[[August Borsig|Borsig]] for use in [[aircraft]].<ref name=":0">{{Cite book |last=Lepage |first=Jean-Denis G. G. |url=https://books.google.com/books?id=hdQBTcscxyQC&dq=MK+108++Rheinmetall&pg=PA54 |title=Aircraft of the Luftwaffe, 1935-1945: An Illustrated Guide |date=2009-03-23 |publisher=McFarland |isbn=978-0-7864-5280-4 |language=en}}</ref>
 The cannon saw  widespread use as an anti-bomber weapon during the second half of the war, first seen in 1943 in the [[Messerschmitt Bf 110|Bf 110G-2]] bomber destroyers and [[Messerschmitt Bf 109|Bf 109G-6/U4]].<ref name=":0" />
-Four MK 108's formed the main armament of the [[Messerschmitt Me 262|Me 262]] the next year.<ref>{{Cite book |last=Forsyth |first=Robert |url=https://books.google.com/books?id=yX-GEAAAQBAJ&newbks=0&printsec=frontcover&pg=PA35&dq=MK+108+Me+262&hl=en |title=Me 262: Northwest Europe 1944–45 |date=2023-01-19 |publisher=Bloomsbury Publishing |isbn=978-1-4728-5053-9 |language=en}}</ref> It could be found on some versions or optional mountings on practically every other German [[fighter aircraft|fighter]] of the era.{{Citation needed|date=May 2023}}
+Four MK 108s formed the main armament of the [[Messerschmitt Me 262|Me 262]] the next year.<ref>{{Cite book |last=Forsyth |first=Robert |url=https://books.google.com/books?id=yX-GEAAAQBAJ&dq=MK+108+Me+262&pg=PA35 |title=Me 262: Northwest Europe 1944–45 |date=2023-01-19 |publisher=Bloomsbury Publishing |isbn=978-1-4728-5053-9 |language=en}}</ref> It could be found on some versions or optional mountings on practically every other German [[fighter aircraft|fighter]] of the era.{{Citation needed|date=May 2023}}
 ==Development==
-The weapon was developed as a private venture by the company in 1940 and was submitted to the ''[[Reich Air Ministry|Reichsluftfahrtministerium]]'' (RLM—Reich Aviation Ministry) in response to a 1942 requirement for a heavy aircraft weapon for use against the [[Allies of World War II|Allied]] heavy [[bomber]]s appearing over German-controlled regions by then. Testing verified that the autocannon was well suited to this role, requiring on average just 4 hits with its 85g [[RDX]]-load (in a 330g shell)  and a resulting strongly [[Brisance|brisant]] high-explosive ammunition, to bring down a [[heavy bomber]] such as a [[B-17 Flying Fortress]] or [[B-24 Liberator]], and just a single "shattering" hit to down a fighter. In comparison, the otherwise excellent 20&nbsp;mm [[MG 151 cannon|MG 151/20]] (18g of HE in a 92g shell) required about 15-20 hits to down a B-17.
+The weapon was developed as a private venture by the company in 1940 and was submitted to the ''[[Reich Air Ministry|Reichsluftfahrtministerium]]'' (RLM—Reich Aviation Ministry) in response to a 1942 requirement for a heavy aircraft weapon for use against the [[Allies of World War II|Allied]] heavy [[bomber]]s appearing over German-controlled regions by then. Testing verified that the autocannon was well suited to this role, requiring on average just four hits with its 85g [[RDX]]-load (in a 330g shell)  and a resulting strongly [[Brisance|brisant]] high-explosive ammunition, to bring down a [[heavy bomber]] such as a [[B-17 Flying Fortress]] or [[B-24 Liberator]], and just a single "shattering" hit to down a fighter. In comparison, the otherwise excellent 20&nbsp;mm [[MG 151 cannon|MG 151/20]] (18g of HE in a 92g shell) required about 15 to 20 hits to down a B-17.
-The MK 108 was quickly ordered into production and was installed in a variety of ''[[Luftwaffe]]'' [[fighter aircraft]]. It saw first operational service in summer 1943 with the [[Messerschmitt Bf 110|Bf 110G-2]] bomber destroyers and in the [[Messerschmitt Bf 109|Bf 109G-6/U4]].<ref>Messerschmitt Bf 109 F,G, & K Series by Jochen Prien, Peter Rodeike page 108.</ref>
+The MK 108 was quickly ordered into production and was installed in a variety of ''[[Luftwaffe]]'' [[fighter aircraft]]. It saw first operational service in summer 1943 with the [[Messerschmitt Bf 110|Bf 110G-2]] bomber destroyers and in the [[Messerschmitt Bf 109|Bf 109G-6/U4]].<ref>Messerschmitt Bf 109 F, G, & K Series by Jochen Prien, Peter Rodeike page 108.</ref>
 ==Design details==
@@ Line 86: / Line 87: @@
 [[File:30mm ammo.JPG|thumb|30x90RB ammunition, as used in the MK 108 Machine Cannon]]
 [[File:MK 108 30mm.JPG|thumb|Side view, MK 108]]
-The cannon used specially-developed 30×90RB&nbsp;mm ammunition—30&nbsp;mm calibre, 90&nbsp;mm case length, [[Rim (firearms)#Rebated rim|rebated]]/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including [[Practice round|practice]], [[Armor-piercing shot and shell|armor-piercing]], [[High-Explosive Ammunition|high-explosive]] and [[Incendiary ammunition|incendiary]]. In operation, however, two major ammunition types were used:  [[mine shell]] and [[high-explosive incendiary]]. The mine shell was made by drawn steel (the same way brass cartridge-cases are made) instead of being forged and machined as was the usual practice for cannon shells.<ref name=":1">{{Cite book |last=Heath |first=Tim |url=https://books.google.com/books?id=S2uEEAAAQBAJ&newbks=0&printsec=frontcover&pg=PT251&dq=MK+108++90+mm+case+length&hl=en |title=In Furious Skies: Flying with Hitler's Luftwaffe in the Second World War |date=2022-09-21 |publisher=Pen and Sword History |isbn=978-1-5267-8524-4 |language=en}}</ref>
+The cannon used specially-developed 30×90RB&nbsp;mm ammunition—30&nbsp;mm calibre, 90&nbsp;mm case length, [[Rim (firearms)#Rebated rim|rebated]]/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including [[Practice round|practice]], [[Armor-piercing shot and shell|armor-piercing]], [[High-Explosive Ammunition|high-explosive]] and [[Incendiary ammunition|incendiary]]. In operation, however, two major ammunition types were used:  [[mine shell]] and [[high-explosive incendiary]]. The mine shell was made by drawn steel (the same way brass cartridge-cases are made) instead of being forged and machined as was the usual practice for cannon shells.<ref name=":1">{{Cite book |last=Heath |first=Tim |url=https://books.google.com/books?id=S2uEEAAAQBAJ&dq=MK+108++90+mm+case+length&pg=PT251 |title=In Furious Skies: Flying with Hitler's Luftwaffe in the Second World War |date=2022-09-21 |publisher=Pen and Sword History |isbn=978-1-5267-8524-4 |language=en}}</ref>
 This resulted in a shell with a thin but strong wall, which hence had a much larger cavity in which to pack a much larger explosive or incendiary charge than was otherwise possible.{{Citation needed|date=May 2023}}
@@ Line 104: / Line 105: @@
 Normally, [[Gas-operated reloading|gas-operated]] or [[Recoil operation|recoil-operated]] mechanisms are used in [[Automatic firearm|automatic weapons]] of rifle calibre and larger because the chamber pressure in such weapons is very high. Therefore, if a simple blowback system (where there is no positive lock between the bolt and barrel) is used, the bolt may recoil and open the breech while the chamber pressure is still high, causing damage to the weapon and split cases (see [[Blowback (firearms)|blowback]] article for more information). To avoid this, simple blowback guns have to use low-powered cartridges or a very heavy bolt.{{Citation needed|date=May 2023}}
-In an Advanced Primer Ignition Blowback design such as the MK 108, the forward motion of the bolt is used instead of a locking mechanism to prevent this premature opening. When the 108 is ready to fire, the bolt and main spring are held back at the rear of the gun, the spring under considerable tension.  When the trigger is squeezed, they are released and shoot forward at a high speed.  The bolt picks up a cartridge and chambers it, but instead of coming to rest against the breech face, it follows the case a small distance into the chamber—which is of course made specially longer in these guns to accommodate this manoeuvre.<ref name=":3">{{Cite book |url=https://books.google.com/books?id=kjt1fYf5BcgC&newbks=0&printsec=frontcover&pg=PA21&dq=MK+108+forward+motion&hl=en |title=Armor |date=1994 |publisher=U.S. Armor Association |language=en}}</ref> Also a cartridge case with a [[rebated rim]] is used, so that the extractor claw can hook over the rim and still fit within the chamber.<ref name=":2">{{Cite book |last=Williams |first=Anthony G. |url=https://books.google.com/books?id=elg2EAAAQBAJ&newbks=0&printsec=frontcover&pg=PT199&dq=characteristic+of+the+APIB+gun+system&hl=en |title=Autocannon: A History of Automatic Cannon and Ammunition |date=2022-08-02 |publisher=The Crowood Press |isbn=978-1-78500-921-1 |language=en}}</ref>
+In an Advanced Primer Ignition Blowback design such as the MK 108, the forward motion of the bolt is used instead of a locking mechanism to prevent this premature opening. When the 108 is ready to fire, the bolt and main spring are held back at the rear of the gun, the spring under considerable tension.  When the trigger is squeezed, they are released and shoot forward at a high speed.  The bolt picks up a cartridge and chambers it, but instead of coming to rest against the breech face, it follows the case a small distance into the chamber—which is of course made specially longer in these guns to accommodate this manoeuvre.<ref name=":3">{{Cite book |url=https://books.google.com/books?id=kjt1fYf5BcgC&dq=MK+108+forward+motion&pg=PA21 |title=Armor |date=1994 |publisher=U.S. Armor Association |language=en}}</ref> Also a cartridge case with a [[rebated rim]] is used, so that the extractor claw can hook over the rim and still fit within the chamber.<ref name=":2">{{Cite book |last=Williams |first=Anthony G. |url=https://books.google.com/books?id=elg2EAAAQBAJ&dq=characteristic+of+the+APIB+gun+system&pg=PT199 |title=Autocannon: A History of Automatic Cannon and Ammunition |date=2022-08-02 |publisher=The Crowood Press |isbn=978-1-78500-921-1 |language=en}}</ref>
 Primer ignition is timed so that the bolt is still moving forward when the propellant is ignited. The expanding gases from the fired round stop the forward motion of the bolt, then reverse its motion. The key characteristic of the APIB system is that, because the resistance due to the weight of the bolt and the mainspring are supplemented by the bolt's considerable forward momentum, the propellant gases are contained in the barrel for critical microseconds, and the projectile will have had time to leave the muzzle, allowing the gas to escape forward and reducing the chamber pressure to a safe level before the bolt and cartridge case emerge from the opposite end.<ref name=":2" />  Once they emerge the weapon cycles like other automatic guns, with one significant exception: instead of simply ejecting the spent cartridge case, the 108 reinserts it into the empty link in the ammunition belt. The heavy bolt continues backwards, compressing the main spring. When the spring is fully compressed it begins to expand forwards again, reversing the motion of the bolt and recommencing the cycle.  This sequence is repeated until the trigger is released or the ammunition is exhausted.<ref name=":3" />
-The APIB design makes practical the use of far more powerful ammunition than with simple blowback operation, but the length and the speed of the bolt's movement within the chamber are limited by the stresses placed on the case by the sliding motion, which takes place under high gas pressure. To keep these within limits either the bolt must be heavy to absorb the pressure, or the barrel must be short to limit the duration of high pressure within the barrel.<ref name=":3" /> The operational tradeoff is that a heavy bolt reduces the rate of fire while a short barrel reduces ballistic performance.{{Citation needed|date=May 2023}} The designers of the MK 108 opted for a high rate of fire and thus used a relatively light bolt, accepting reduced ballistic performance due to the corresponding necessity of a short barrel. As a result, the MK 108 had a muzzle velocity of only 540&nbsp;m/s,<ref name=":0" /> compared to the approx. 800&nbsp;m/s for the [[MG 151 cannon|MG 151/20]].<ref>{{Cite book |last=Bernstein |first=Jonathan |url=https://books.google.com/books?id=SMQpEAAAQBAJ&newbks=0&printsec=frontcover&pg=PA34&dq=MG+151/20++muzzle&hl=en |title=P-47 Thunderbolt vs German Flak Defenses: Western Europe 1943–45 |date=2021-10-28 |publisher=Bloomsbury Publishing |isbn=978-1-4728-4630-3 |language=en}}</ref>
+The APIB design makes practical the use of far more powerful ammunition than with simple blowback operation, but the length and the speed of the bolt's movement within the chamber are limited by the stresses placed on the case by the sliding motion, which takes place under high gas pressure. To keep these within limits either the bolt must be heavy to absorb the pressure, or the barrel must be short to limit the duration of high pressure within the barrel.<ref name=":3" /> The operational tradeoff is that a heavy bolt reduces the rate of fire while a short barrel reduces ballistic performance.{{Citation needed|date=May 2023}} The designers of the MK 108 opted for a high rate of fire and thus used a relatively light bolt, accepting reduced ballistic performance due to the corresponding necessity of a short barrel. As a result, the MK 108 had a muzzle velocity of only 540&nbsp;m/s,<ref name=":0" /> compared to the approx. 800&nbsp;m/s for the [[MG 151 cannon|MG 151/20]].<ref>{{Cite book |last=Bernstein |first=Jonathan |url=https://books.google.com/books?id=SMQpEAAAQBAJ&dq=MG+151/20++muzzle&pg=PA34 |title=P-47 Thunderbolt vs German Flak Defenses: Western Europe 1943–45 |date=2021-10-28 |publisher=Bloomsbury Publishing |isbn=978-1-4728-4630-3 |language=en}}</ref>
-Another significant feature is that, in the APIB system [[Blowback (firearms)#Advanced primer ignition (API) blowback|the cycle starts with the bolt open]], which prevents an [[autocannon]] using the APIB principle from being accurately [[Synchronization gear|synchronized with an aircraft's propeller]].<ref>{{Cite book |last=Williams |first=Anthony G. |url=https://books.google.com/books?id=elg2EAAAQBAJ&newbks=0&printsec=frontcover&pg=PT181&dq=API+Blowback+synchronized+with+an+aircraft's+propeller.&hl=en |title=Autocannon: A History of Automatic Cannon and Ammunition |date=2022-08-02 |publisher=The Crowood Press |isbn=978-1-78500-921-1 |language=en}}</ref>
+Another significant feature is that, in the APIB system [[Blowback (firearms)#Advanced primer ignition (API) blowback|the cycle starts with the bolt open]], which prevents an [[autocannon]] using the APIB principle from being accurately [[Synchronization gear|synchronized with an aircraft's propeller]].<ref name=":2" />
 <gallery class="center" caption="MK 108 bolt cycle" heights="400px" widths="300px">
@@ Line 124: / Line 125: @@
 [[File:Me262.1823.png|Left pair in an Me 262|thumb|right]]
-The MK 108 saw widespread use among fighters tasked with shooting down enemy bombers. Some of the aircraft deploying, or intended to be armed with, the MK 108 were [[Messerschmitt Bf 109]],<ref>{{Cite book |last=Jackson |first=Robert |url=https://books.google.com/books?id=srPNDwAAQBAJ&newbks=0&printsec=frontcover&pg=PT37&dq=MK+108++Messerschmitt+Bf+109&hl=en |title=Messerschmitt Bf 109 |date=2018-07-30 |publisher=Pen and Sword |isbn=978-1-5267-1055-0 |language=en}}</ref> [[Messerschmitt Bf 110]],<ref>{{Cite book |last=III |first=Marshall Michel |url=https://books.google.com/books?id=nGCWDwAAQBAJ&newbks=0&printsec=frontcover&pg=PA30&dq=MK+108++Messerschmitt+Bf+110&hl=en |title=Schweinfurt–Regensburg 1943: Eighth Air Force’s costly early daylight battles |date=2020-01-23 |publisher=Bloomsbury Publishing |isbn=978-1-4728-3868-1 |language=en}}</ref> [[Messerschmitt Me 163]], [[Messerschmitt Me 262]], [[Focke-Wulf Fw 190]], [[Focke-Wulf Ta 152]], [[Focke-Wulf Ta 154]], [[Heinkel He 162]], [[Heinkel He 219]], [[Horten Ho 229]] and [[Junkers Ju 388]].
+The MK 108 saw widespread use among fighters tasked with shooting down enemy bombers. Some of the aircraft deploying, or intended to be armed with, the MK 108 were [[Messerschmitt Bf 109]],<ref>{{Cite book |last=Jackson |first=Robert |url=https://books.google.com/books?id=srPNDwAAQBAJ&dq=MK+108++Messerschmitt+Bf+109&pg=PT37 |title=Messerschmitt Bf 109 |date=2018-07-30 |publisher=Pen and Sword |isbn=978-1-5267-1055-0 |language=en}}</ref> [[Messerschmitt Bf 110]],<ref>{{Cite book |last=III |first=Marshall Michel |url=https://books.google.com/books?id=nGCWDwAAQBAJ&dq=MK+108++Messerschmitt+Bf+110&pg=PA30 |title=Schweinfurt–Regensburg 1943: Eighth Air Force's costly early daylight battles |date=2020-01-23 |publisher=Bloomsbury Publishing |isbn=978-1-4728-3868-1 |language=en}}</ref> [[Messerschmitt Me 163]],<ref>{{Cite book |last=Graff |first=Cory |url=https://books.google.com/books?id=DyzRBQAAQBAJ&dq=MK+108++Messerschmitt+Me+163&pg=PA220 |title=Flying Warbirds: An Illustrated Profile of the Flying Heritage Collection's Rare WWII-Era Aircraft |date=2014-11-01 |publisher=Zenith Press |isbn=978-1-62788-495-2 |language=en}}</ref> [[Messerschmitt Me 262]],<ref>{{Cite book |last1=Oehler |first1=Robert |url=https://books.google.com/books?id=3ZujCwAAQBAJ&dq=MK+108++Messerschmitt+Me+262&pg=PA5 |title=Modelling the Messerschmitt Me 262 |last2=Green |first2=Brett |date=2012-04-20 |publisher=Bloomsbury Publishing |isbn=978-1-78096-686-1 |language=en}}</ref> [[Focke-Wulf Fw 190]],<ref name=":4">{{Cite book |last=Graf |first=Mantelli-Brown- Kittel- |url=https://books.google.com/books?id=cFs8DgAAQBAJ&dq=MK+108++Focke-Wulf+Fw+190&pg=PA79 |title=The Focke-Wulf Fw 190 |date=2017-02-28 |publisher=Edizioni R.E.I. |isbn=978-2-37297-325-0 |language=it}}</ref> [[Focke-Wulf Ta 152]],<ref name=":4" /> [[Focke-Wulf Ta 154]],<ref name=":5">{{Cite book |last=Stemp |first=P. D. |url=https://books.google.com/books?id=oWIeBQAAQBAJ&dq=MK+108++Focke-Wulf+Ta+154&pg=PA422 |title=Kites, Birds & Stuff - Aircraft of GERMANY - E to H |date=2013-04-19 |publisher=Lulu.com |isbn=978-1-291-29268-8 |language=en}}</ref> [[Heinkel He 162]],<ref>{{Cite book |last=Dorr |first=Robert F. |url=https://books.google.com/books?id=-nBmAgAAQBAJ&dq=MK+108++Heinkel+He+162&pg=PA276 |title=Fighting Hitler's Jets: The Extraordinary Story of the American Airmen Who Beat the Luftwaffe and Defeated Nazi Germany |date=2013-11-15 |publisher=Voyageur Press |isbn=978-0-7603-4398-2 |language=en}}</ref> [[Heinkel He 219]],<ref name=":5" /> [[Horten Ho 229]]<ref>{{Cite book |last=Metzmacher |first=Andreas |url=https://books.google.com/books?id=YYhSEAAAQBAJ&dq=MK+108++Horten+Ho+229&pg=PA2024 |title=Gotha Aircraft: From the London Bomber to the Flying Wing Jet Fighter |date=2021-12-02 |publisher=Fonthill Media |language=en}}</ref> and [[Junkers Ju 388]].<ref>{{Cite book |last=Forsyth |first=Robert |url=https://books.google.com/books?id=MZRoEAAAQBAJ&dq=MK+108++Junkers+Ju+388&pg=PA65 |title=Junkers Ju 188 Units of World War 2 |date=2022-06-23 |publisher=Bloomsbury Publishing |isbn=978-1-4728-3636-6 |language=en}}</ref>
-The MK 108 was also fitted to [[night fighter]]s in an unusual installation, called "''[[Schräge Musik]]''" (German colloquialism: "jazz",<ref>Gustin, Emmanuel. [http://users.skynet.be/Emmanuel.Gustin/fgun/fgun-uf.html "Upward firing guns."] ''The WWII Fighter Gun Debate,'' 1999. Retrieved: 18 June 2012.</ref> literally "awkward music" or "slanted music"). In this configuration, the cannons were mounted in the fuselage, aiming upwards and ''slightly'' forwards at an oblique (18 to 30 degree) angle, depending on fitment and aircraft. This allowed the night fighter to attack bombers, often undetected, by approaching from underneath the enemy aircraft - many British heavy bombers had neither weapons on the ventral fuselage nor windows for vision. This installation was so effective that discovery and news of its adoption was much slower than usual in reaching British night-bombing forces, as there were rarely any survivors from the attacks to report the new threat. This system was fitted to some versions of the He 219 Uhu, late-model Bf 110 night fighters, Junkers [[Ju 88]] & 388 and the Dornier [[Dornier Do 217#Do 217N|Do 217N]] model. It was also fitted more rarely to the (prototype) Focke-Wulf Ta 154 and [[Fw 189]] along with the planned, two-seat Me 262B-2 jet night-fighter. In the latter case this produced a jet fighter with six MK108 cannons - with the fitment of the projected [[Neptun radar|mass-produced, mid-VHF band FuG 218 radar]].
+The MK 108 was also fitted to [[night fighter]]s in an unusual installation, called "''[[Schräge Musik]]''" (literally "awkward music" or "slanted music"). In this configuration, the cannons were mounted in the fuselage, aiming upwards and ''slightly'' forwards at an oblique (18 to 30 degree) angle, depending on fitment and aircraft. This allowed the night fighter to attack bombers, often undetected, by approaching from underneath the enemy aircraft - many British heavy bombers had neither weapons on the ventral fuselage nor windows for vision. This installation was so effective that discovery and news of its adoption was much slower than usual in reaching British night-bombing forces, as there were rarely any survivors from the attacks to report the new threat. This system was fitted to some versions of the He 219 Uhu, late-model Bf 110 night fighters, Junkers [[Junkers Ju 88|Ju 88]] & 388 and the Dornier [[Dornier Do 217#Do 217N|Do 217N]] model. It was also fitted more rarely to the (prototype) Focke-Wulf Ta 154 and [[Fw 189]] along with the planned, two-seat Me 262B-2 jet night-fighter. In the latter case this produced a jet fighter with six MK108 cannons - with the fitment of the projected [[Neptun radar|mass-produced, mid-VHF band FuG 218 radar]].
 == Related designs ==
@@ Line 161: / Line 162: @@
 |crew=
 <!-- Ranged weapon specifications -->
-|cartridge=55 × 175RB mm (1485 g)
+|cartridge=55×175RBmm (1485 g)
 |caliber=55 mm
-|action=[[Blowback (firearms)|Blowback operation]]
+|action=[[API blowback]]
 |rate=300 rounds/min
 |velocity=594 m/s (1,950 ft/s)
@@ Line 202: / Line 203: @@
 ==See also==
+*[[List of API blowback firearms]]
 *[[MK 101 cannon]]
 *[[MK 103 cannon]]
@@ Line 214: / Line 216: @@
 ==External links==
 * [http://www.xs4all.nl/~robdebie/me163/weapons15.htm MK 108 ammunition types]
-* [http://www.quarryhs.co.uk/WW2guneffect.htm World War 2 Fighter gun effectiveness comparison]
+* [http://www.quarryhs.co.uk/WW2guneffect.htm World War 2 Fighter gun effectiveness comparison] {{Webarchive|url=https://web.archive.org/web/20171030102939/http://quarryhs.co.uk/WW2guneffect.htm |date=30 October 2017 }}
 * [https://web.archive.org/web/20090113130439/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=1041 factsheet] from the [[National Museum of the United States Air Force]], Dayton, Ohio
 * [https://web.archive.org/web/20160304134142/http://www.deutscheluftwaffe.de/archiv/Dokumente/ABC/m/MK%20108/rheinmetall108.htm German language page on the MK 108 autocannon]
@@ Line 220: / Line 222: @@
 {{Subject bar
 | portal1=Aviation
-| portal2=Military of Germany
-| portal3=World War II
 | commons=y
 }}
+{{API blowback firearms}}
 {{Rheinmetall}}
 {{WWIIGermanAerialWeapons}}

v t e API blowback firearms
Assault rifles	APT
Anti-tank rifles	Oerlikon SSG36 Solothurn S-18/100
Autocannons	Becker Type M2 Oerlikon 20 mm Type 99 cannon MK 108 cannon
Grenade launchers	Daewoo K4 Heckler & Koch GMG Mk 19 grenade launcher QLU-11 (LG5)
Shotguns	Atchisson AA-12
Submachine guns	Sterling SMG TZ-45
Machine guns	QJZ-171

v t e Rheinmetall
Subsidiaries	KSPG Maschinenbau Kiel Mauser Rheinmetall Air Defence Rheinmetall Algeria Rheinmetall MAN Military Vehicles Rheinmetall BAE Systems Land
Current products	Boxer IdZ LGI Mle F1 LIV (SO) Serval LLM01 MAN LX and FX ranges of tactical trucks RMMV HX range of tactical trucks MANTIS Air Defence System Mauser BK-27 Mungo ESK Nanuk Remotely Controlled Weapon Station Rheinmetall Seahawk Rheinmetall Oerlikon Millennium Gun Rheinmetall Sea Snake 30 mm Puma (IFV) Rheinmetall 120 mm gun Rheinmetall KZO Rheinmetall LTA2 Rheinmetall MG 3 Rheinmetall MG 60 Rheinmetall Rh 202 Rheinmetall RMG.50 Rheinmetall RMG 7.62 Rheinmetall RMK30 Rheinmetall YAK TPz Fuchs Wiesel AWC Wisent Lynx
Legacy products	3.7 cm Pak 36 5 cm Pak 38 7.5 cm KwK 42 7.5 cm Pak 40 7.5 cm FK 16 nA 7.5 cm Leichtgeschütz 40 8 cm PAW 600 8.8 cm Flak 18/36/37/41 10 cm Nebelwerfer 35 10 cm Nebelwerfer 40 10.5 cm Leichtgeschütz 42 10.5 cm leFH 16 10.5 cm leFH 18 15 cm Nebelwerfer 41 15 cm sIG 33 38 cm schwerer Ladungswerfer MG 42 MK 108 cannon MK 115 cannon Ordnance QF 15 pounder Solothurn S-18/1000 Solothurn ST-5

v t e German aerial weapons of the Second World War
Machine guns	MG 15 MG 17 MG 81 & 81Z MG 131
Autocannons	MG FF MG 151 MK 101 MK 103 MK 108 MK 214A Schräge Musik
Anti-tank autocannons	BK 3.7 BK 5 BK 7.5
Unguided rockets	Panzerblitz R4M Werfer-Granate 21
Guided bombs and missiles	Fritz X Hs 117H Hs 293 V-1 flying bomb
Anti-personnel bombs	SD 1 SD 1 FRZ SD 2 SD 10 A SD 10 FRZ SD 10 C SD 15 SBe 50 SD 50 SD 70 SBe 250 SD 250 SD 500 SD 500A SD 500E SD 1400 SD 1700
Armor-piercing bombs	PC 500 PC 1000 PC 1400 PC 1600 PC 500 Rs PC 1000 Rs PC 1800 Rs PD 500 PD 1000 SC 10 SC 10 DW SD 4 HL SD 4/HL RS SD 9/HL
Cluster bombs	AB 23 AB 250-2 AB 250-3 AB 500-1 AB 500-1B AB 500-3A AB 70-D1 BDC 10
High-explosive bombs	SB 1000 SB 1800 SB 2500 SC 50 SC 100 SC 250 SC 500 SC 1000 SC 1200 SC 1800 SC 2000 SC 2500
Incendiary bombs	Br C 50 Br C 100 Br C 250 Flam 50 Flam 100 Flam 250
Anti-ship bombs	PC 500 RS "Paulina" PC 1000 RS "Paul" PC 1800 RS "Panther" SB 800R-5 250 SB 800RS
Smoke bombs	NC 50
Experimental weapons	Blohm & Voss BV 143 Blohm & Voss BV 246 Blohm & Voss BV 950 BT 200 Henschel Hs 294 Henschel Hs 298 Jagdfaust MG 213 MK 112 MK 214A MK 115 Ruhrstahl X-4 SG 116 [de]