I’m not doubting your word - I was just after more detail!
Tony Williams: Military gun and ammunition website and discussion forum
Okay.
Mauser family Part 3, MG 151/20:
Despite the good characteristics in the 15 mm MG the german Air Force promptly favored the 20 mm gun. The air-to-air doctrine was turn to believe that is more likely to destroy an aircraft with high explosive shells and not just putting holes on it with AP ammunition.
The 20 mm diameter was always considerer as the minimum practical explosive shell. The MG-151 was designed to accept all the family of the FF, including the high capacity Minen bullet.
There was some limitations to employ the same receiver and bolt of the 15 mm variant , the cartridge case had to be reduced in length, that and the heavier projectile gave as result a 100 m/s reduction in muzzle velocity compared with the 151/15. A shorter stroke in the bolts travel was however good for the rate of fire , about 780-800 rpm. It can handle bullets between 92 and 120 grams.
Mauser began the high scale production in 1941 and it was adopted first by the Bf-109F-4 in mid-1941. The MG-151 quickly replaced (or at list it was intended so) the older MG-FF in several types of aircraft. There was a pneumatically triggered variant for fixed mounting and other manually charged for flexible defensive laffettes. As usual the cannon was feed by a disintegrable metallic belt and air cooled. The cannon weights 42 kg, and it had a overall length of 1620 mm.
Flexible MG-151/20
It will be superfluous to describe all the aircraft wich employs this gun, some like the Me-109, Fw-190, Me-110G, Ju-88C, Ju-88G, Ju-87D, Me-210/ Me-410, He-177, FW-200, etc. It enough to say the it became the most used cannon trough the war
Gun layout in a Me-210.
Double nose mounting in night fighter Me-110G-4, note the large flash hidders.
Compared with the allied guns like the Hispano Mk-II the Mauser 20 mm was little less powerful, it had in his favor a much superior reliability and rate of fire. In the MG-151 the german pilot could be sure that in the 99,99% times he pulls the trigger the Mauser went off…thing that cannot be reproduced in the French-British cannon.
It might be worth mentioning that both 15mm and 20mm versions of the MG 151 were available with either percussion or electric priming. The ammunition was not interchangeable between the two types. The electric-primed ones were used in synchronised applications, which means almost entirely the wing-root guns in the Fw 190. The percussion guns were used in the Bf 109.
Tony Williams: Military gun and ammunition website and discussion forum
Thanks for your adds Tony, incidentally I going to put some of that later.
Motorkanone Mg-151/20 in B-109F.
Container MB-151 below Me-109G-4/R6.
Mg-151/20 with open sights.
Quadruple “Schräge musik” emplacement.
An addition to my last post: I should have said that all MG 151 guns fitted to the Fw 190 family were electric primed, not just the synchronised ones. This was done to simplify the job of the armourers, because the two types of ammunition were difficult to tell apart.
For the same reason, one interesting addition to the Bf 109G-6 was not adopted - the fitting of an MG 151 under the fuselage, to fire through the prop. This apparently worked very well, providing a valuable improvement in firepower without the performance and handling penalties of the underwing pods. However, the belly gun had to be synchronised, which meant it had to use the electric-primed gun, whereas the engine gun used percussion priming. The risk of mixing up the ammo was considered too great, so the idea was dropped.
Tony Williams: Military gun and ammunition website and discussion forum
For the same reason, one interesting addition to the Bf 109G-6 was not adopted - the fitting of an MG 151 under the fuselage, to fire through the prop. This apparently worked very well, providing a valuable improvement in firepower without the performance and handling penalties of the underwing pods. However, the belly gun had to be synchronised, which meant it had to use the electric-primed gun, whereas the engine gun used percussion priming. The risk of mixing up the ammo was considered too great, so the idea was dropped
Mg-151/20E below Bf-109G-4.
Mg-151/20 Elecktrish.
No much to add to Tony s post. The differences with the normal MG-151/20 was purely internal. The spring loaded firing pin was replaced with a fixed needle wich was energizated by the 24v aicraft electric circuit. The sincronization device consisten in a electromechanical gear, the use of electricar primer wich was detonated by a spark, mean that a more instantaneous ignition was provided. that allowed the Mg-151/20E to shoot trough a high rpm 3 thick blade propellers like the BMW 801 engine and still had a rate over the 600 rpm. The production of the Mg-151/20E were delivered almost entirely to the Fw-190 and the Ta-152H variants, some other aircraft in use were the Do-335 ( 2 above the engine), Me-209 stüfe II (wingroots) and the Me-309 (wingroots and above engine)
The 4 guns in a FW-190A-6.
15x96mm Ammunition for the MG-151/15.
Panzergranatpatrone, L-spur.
Armor piercing steel shot, with tracer, projectile weight 72 grams initial speed 850 m/s. The tracer elemente endure at list 1100 meters.
Penetration table for Pzg.Ptr. L-spur. 25 mm at 100 meters and 13 mm at 600 meters, both in vertical (90º) plate and direct mode..
Brandsprenggranatpatrone
Incendiary-explosive. 57,5 grams bullet, muzzle velocity 960 m/s, pretty fast one.
Brandsprenggranate L-spur Mit Zerl.
Same as above but with an tracer and self destruction element in the bullet base. Green band.
and also…
Hartkern-Panzergranate ohne-zerl.
This is a pretty unusual variant. It consist in a miniaturized hard core Panzergranate 40 as used in the Panzers. Bullet weight 53,5 grams, it had an 9,5mm diameter tugsten-carbide core with a aluminium-magnesium envelope. It was propelled by 24,5 grams of gunpodwer an it can reach 1000 m/s. Due his cost a relative rarity it was to combat tanks only, no for air-to-air use. Probably it went to the Hs-129B-1 attack craft, and for some experimental 15 mm antitank rifles.
Penetration table of the Hartkern 15 mm bullet, 48mmm at 100 meters in a 160 kg/square mm steel ( wich is equivalent to a SAE 4340 alloy), excellent figure…
20x82mm ammo for MG-151/20.
This was the result of the necked up 15mm cartrigde, it was available with brass or steel case, the steel being favored because the always problematic copper resources, more than 80% of the cases wre fabricated in the metal. The ammo for the E variant used a electric primer, the other an standar percusion primer. There was at list 30 variant of projectile for 20x82mm cartrigde including several ubung (exercise) ones, for space reason I will only post the most used in wartime,
Brandsprenggranate glimmspur mit Zerleger.
Explosive-incendiary, with glowing tracer and self destruction fuse, a “working” ammo for the MG-151/20. Bullet weight 115 grams, explosive content 6 grams, the self destruccion device actuate after 1100 meters from the muzzle, o 3 seconds in flight. Muzzle speed about 720 m/s.
Minengesschos.
The thin walled explosive projectile from the FF/M adapted to the MG-151, Weight 92 grams, muzzle speed 785 m/s.
Minengesschos mit Zerleger.
Same as above but with an self destructing device, indicated by a green band stenciled in the bullet. A good decition specially in later war when most of the air combat were fought over the homeland.
continue…
…continue from above.
Panzersprenggranate.
Armor piercing-explosive, weight 117 grams , muzle velocity 705 m/s. A steel shot with a 5 grams of nitropenta, base fused. Explosive content indicate by a yellow band.
Penetration table por the 20 mm Pzgr. 24 mm at 100 meters (90 º incidence) in 140 kg/squre mm steel, equivalent to a SAE 4140 alloy. The discontinued line indicated penetration after get trough a 3 mm 20 º tilted duraluminium plate.
Panzergranate mit Phosphor
Armor piercing incendiary, filled with an red and white phosphorous mix. 117 grams bullet, muzzle speed 705 m/s.
Panzergranate-Elektron.
AP incendiary, 117 grams, filled with a incendiary mix called “Elektronthermit”, the characteristics of this were such as once iniciated it can burn even underwater because it had his own provition of O2. Muzzle speed 695-700 M/s. This variant were used mostly by the maritime and recce aircraft like FW-200C, Ju-88A-14, Ju-290, He-177, Bv-138, etc.
…continue from above:
And at last but no at list:
Brandgranate-G-spur.
Completely incendiary ammunition, with tracer, painted entirely in blue. filled with a mix of phosphor and magnesium, 116 grams bullet 710 m/s Muzzle speed. Used with good effect by the night fighters, there was a variant with self-destrution also.
Maschinen Kanone MK-101 de 30mm. Part 1
The search for a gun potent enough to face and defeat bombers with few shots gave as result the delopment of the Rheinmetall MK-101 of 30mm calibre. His development began in 1935 ( simultaneously with other weapons) and in 1940 it was ready to large scale production.
Functioning principle:
The working mechanisns in the Mk-101 is one in wich the barrel and bolt recoiled 3 cm backwards afer the shot. The bolt in locked and open for by a locking sleeve, this sleeve have an internal interrupted treads, and is rotated by and milled lugs in the barrel jacket, the sleeve rotation open and closed the chamber. This system was patented by Louis Stange in the late 1920s and used in some Solothurn MGs like the Mg-29, and Mg-30.
In the Mk-101 gave a strong locking system but a slow rate of fire, about 250 rpm.
This 30 mm automatic cannon weights (unloaded) 176 kg, had an overall lenght of 2640 mm, is pneumatically triggered and feeded by a 30 rounds drum magazine.
In service:
The Mk-101 was first introduced in the heavy fighter Me-110C-6. There was big plans for this fighter and his armament. Almost the entire production of Me-110C-6 went to the special formation Erprobungsgruppe 210, this group had the task to test special weapons and tactics, ( and teorically introduce the Me-210 in front line service) also it participated in the attacks against the radar station and naval transports of Britain coast. The C-6 had his MG-FF guns deleted to save weight. After some successes the disaster struck the Erpbg 210 formation when it lost his commander Walther Rubensdoffer to the Spitfires.
Me-110C-6 with ventral Mk-101.
The same without fairing.
The surviving aircraft wen to some ZG heavy fighter squadrons.
The 30-round drum was introduced in the Hs 129 installation. The Bf 110C-6 used box magazines: some sources say only six rounds capacity but a contemporary British report, which examined a plane shot down in August 1940, reported finding several ten-round magazines (which could evidently be changed in flight by the gunner).
Tony Williams: Military gun and ammunition website and discussion forum
Interesting, I have only knowledge of the 30 shot magazine. In combaat the gunner must be changing clips like crazy . It should be interesting to see what was the effect of a 30mm bullet in a Hurricane or Spitfire.
As I understand it the 110C-6 was used principally in ground attack missions (very effective against 1940-era tanks, I believe). The British reported that the ammo mags were loaded alternately with AP and HE.
Tony Williams: Military gun and ammunition website and discussion forum
Part 2, Antiarmor usage.
As I understand it the 110C-6 was used principally in ground attack missions (very effective against 1940-era tanks, I believe). The British reported that the ammo mags were loaded alternately with AP and HE
Thank for the aditional info.
As far I know the Mk-101 was seriously consider to the antiarmor use after some test in Rechlin in winter 1941-42. The penetration of the of steel AP bullet was pretty average but with the newly designed H-Panzergrante L-spur the Mk-101 probe to be a winner.
Further test was done in the Kummersdorf tank probe facility against some captured tanks. The MK-101 with tugsten core was devastating against the T-34 , and a 50 % of the bullets fired on the side plate of a KV-1 penetrated, the shot on the top and engine coves were also very efective.
Some pics: effect of MK-101 tugsten ammo in KV-1 heavy tank.
On a point of detail, the gun in the 110C-6 shot down in the BoB was stamped MG 101 - the MK designation was applied later (1941-2?)
Tony Williams: Military gun and ammunition website and discussion forum
That is a weird designation.
Mk-101 in Hs-129B.
The cannon was introduced in the B-1/R3 subvariant and then used in the B-1 & B-2 until it was replaced by the MK-103. With the MK 101 the Henschel 129 was rised from a mediocre attack aircraft to a powerful close support plataform.
Squematic MK 101 in Hs-129, note the compressed air bottles for charging.
In Hs-129B-2, in manteinance position
In flight position.
I think that at the time, they had not invented the MK designation at all - any automatic gun was described as MG, regardless of calibre. The distinction between 30mm guns and the smaller ones was only introduced during the course of the war.
The later guns which were bigger than 30mm were of course designated BK for Bordkanon (interesting that the current 27mm Mauser aircraft gun should be designated “BK 27”).
Tony Williams: Military gun and ammunition website and discussion forum
They probably not. I think that was in 1942 when the designation number were assigned, 100 and some for the Rheinmethall guns( Mk-108, 112), 200 for the Mauser ( Mg-213,214) and 300s for the Krieghoff and other gunmakers.
Is worth to mention that this cannon was also used in a double turret in the He-177.
And was "re-introduced " in some Bf-110Es and employed against tanks in the African desert.
