Kriegsmarine 30mm AA Latewar Development?

[_Sarcasticat_]

I was curious if anyone had better information regarding Germany's - particularly the Kriegsmarine - latewar 30mm weaponry development. The extent of my knowledge in this field is probably not significantly advanced over most. I am aware of the 3cm MK 103 in Flakvierling and Flak 28 mountings (Jaboschrek if I am recalling the name correctly), the latter of which has early, middle, and late variants of the mount. Additionally, I am aware of even a 3.7cm Flak 37 (!) in a Flakvierling, which was tested and unsurprisingly found unsat.
Directly related to 3cm Flak M44 development, I can't say I know or understand too much. I've heard that the 3cm Flak M44 and MK 303 are different, one being from Mauser and/or Rheinmetall - likely as competing designs - and the other Brno (hence "MK 303(Br)").

The development, specifications, and photographic material related to these weapons are incredibly sparse. I was wondering if anyone had anything beyond this.

 

[Tony Williams]

From my forthcoming history of automatic cannon and their ammunition:

3 cm MK 303: 30 x 211 ammunition

This high-velocity gun was developed during WW2 at Brünner Waffenwerke in Czechoslovakia under German control, with the involvement of Krieghoff. It was a gas-operated design using a horizontal wedge lock and seems to have been a scaled-up version of the 2 cm MG 301 (see above). It used "frame feeding" (10-round skeletal magazines). It weighed 185 kg, was 295 cm long with an L/73 barrel and fired at 400 rpm. It was intended for naval Flak applications (initially in Type XXI submarines) but was not ready in time. After the war, development was continued by Czechoslovakia and it entered service with the Czech and other armies in a twin AA mounting, designated M53.

I have no data on a 3 cm M44.

 

[_Sarcasticat_]

-snip-

I have no data on a 3 cm M44.

Thank you, anything is better than nothing.

The place I've heard of the differing developments from other factories comes from an older topic here, this topic specifically:

https://www.secretprojects.co.uk/threads/3cm-flak-m44-and-others.19737/#post-191329

The post(s) by Wurger.

 

[Tony Williams]

-snip-

I have no data on a 3 cm M44.

Thank you, anything is better than nothing.

The place I've heard of the differing developments from other factories comes from an older topic here, this topic specifically:

https://www.secretprojects.co.uk/threads/3cm-flak-m44-and-others.19737/#post-191329

The post(s) by Wurger.

I have been doing a bit more digging, since I'd like to sort this out for myself! I have copies of the Unterlüß reports as well as Musgrave and have found more information, but there is little data and some of it is confusing.

Musgrave states on page 198 (1992 edition) that the "3cm Flak 44" was by Rheinmetall, but on page 566 includes a "3cm Flak M.44" in a list of Mauser projects.

There are three relevant Unterlüß documents, listing the guns, the ammunition and the mountings.

The gun document includes the following 3 cm projects (among others):
MK 411 (engine-driven, 900 m/s)
Mk 303 (Brünner Waffenwerke); 400 rpm; 185 kg; 1,060 m/s; gas operated; naval Flak for U-Boote and S-Boote.
3 cm Flak M 44 (300M); Mauser project; gas operated; 400 rpm; 100 kg; 920 m/s.
3 cm Flak 4M 44 (I think - I only have a poor quality photocopy); Rheinmetall-Borsig (competitor for the above); 420 rpm; 140 kg; 920 m/s.

The ammunition document includes:
3 cm MK 411 HE-T; 440 g; 900 m/s
3 cm MK 303 (Br); M-Geschoss 330 g (72 g HE); 1100 m/s

The mounting document includes:
3 cm Flak M 44 twin mounting for S-Boote; 690 kg.

One curiosity is that I have the following note:

"2,8 cm Gerät 411: 28 x 216B ammunition.

A Krupp project initiated in 1941 for a motor cannon driven by the aircraft engine, and therefore presumably limited to use with vee-engines, with the gun fitting between the cylinder banks and firing through a hollow propeller hub. This used a large and powerful cartridge, but was unsuccessful. It is sometimes confused with the 3 cm MK 411, about which virtually nothing seems to be known except the calibre."

So - how does the 2,8 cm Gerät 411 match up with the 3 cm MK 411???

 

[_Sarcasticat_]

-snip-

I have no data on a 3 cm M44.

Thank you, anything is better than nothing.

The place I've heard of the differing developments from other factories comes from an older topic here, this topic specifically:

https://www.secretprojects.co.uk/threads/3cm-flak-m44-and-others.19737/#post-191329

The post(s) by Wurger.

I have been doing a bit more digging, since I'd like to sort this out for myself! I have copies of the Unterlüß reports as well as Musgrave and have found more information, but there is little data and some of it is confusing.

Musgrave states on page 198 (1992 edition) that the "3cm Flak 44" was by Rheinmetall, but on page 566 includes a "3cm Flak M.44" in a list of Mauser projects.

There are three relevant Unterlüß documents, listing the guns, the ammunition and the mountings.

The gun document includes the following 3 cm projects (among others):
MK 411 (engine-driven, 900 m/s)
Mk 303 (Brünner Waffenwerke); 400 rpm; 185 kg; 1,060 m/s; gas operated; naval Flak for U-Boote and S-Boote.
3 cm Flak M 44 (300M); Mauser project; gas operated; 400 rpm; 100 kg; 920 m/s.
3 cm Flak 4M 44 (I think - I only have a poor quality photocopy); Rheinmetall-Borsig (competitor for the above); 420 rpm; 140 kg; 920 m/s.

The ammunition document includes:
3 cm MK 411 HE-T; 440 g; 900 m/s
3 cm MK 303 (Br); M-Geschoss 330 g (72 g HE); 1100 m/s

The mounting document includes:
3 cm Flak M 44 twin mounting for S-Boote; 690 kg.

One curiosity is that I have the following note:

"2,8 cm Gerät 411: 28 x 216B ammunition.

A Krupp project initiated in 1941 for a motor cannon driven by the aircraft engine, and therefore presumably limited to use with vee-engines, with the gun fitting between the cylinder banks and firing through a hollow propeller hub. This used a large and powerful cartridge, but was unsuccessful. It is sometimes confused with the 3 cm MK 411, about which virtually nothing seems to be known except the calibre."

So - how does the 2,8 cm Gerät 411 match up with the 3 cm MK 411???

Well that's likely more than most for such a vague and specific topic.

Based on the popularity I can only assume that the MK 303 only ever reached beyond prototype stage and into production, although it never appeared on the intended Type XXI U-Boats (though I have heard tell of them being experimentally mounted to a few). The Rheinmetall and Mauser projects might have been competitors or maybe a variant for other branches despite the fact that an AA armaments unification was sort-of ongoing (as at least suggested by the 3.7cm/57 Flak M43, the navalized 3.7cm Flak 37).
Another note would be that I've heard the Brunner Waffenwerke 3cm be called the "3cm Flak M44" alternatively, which also seems to give credit that it may have been a competitor design with the official designation "MK 303".

As for the 2.8cm, I have no idea. Kind of reminds me of the squeezebore 2.8cm PaK though.

 

[Tony Williams]

the 3.7cm/57 Flak M43, the navalized 3.7cm Flak 37

Not quite. The standard Luftwaffe/Army 3,7 cm AA gun was designated the Flak 18, 36 or 37. The gun and ammo were identical, but the Flak 36 had a better mounting while the Flak 37 was fitted to use more advanced sights. They were never intended for fitting to ships (although some were).

The Flak M43 was a new design with a different operating system (but the same ammo), intended from the start to be the all-service AA gun.

On the naval side, they had the manually-loaded SK/C-30 guns firing much more powerful ammo. In the late 1930s the automatic SK/C-36 (Bofors copy) briefly emerged, with its own unique ammo. This was later developed into the Flak M42. The Flak M43 was intended to be the replacement, but it was all too late to make a difference.

 

[Tony Williams]

As for the 2.8cm, I have no idea. Kind of reminds me of the squeezebore 2.8cm PaK though.

Yes, there was an automatic aircraft gun which fired 2.8/2cm squeezebore ammo, although the cartridge case was different from the army manually-loaded gun.

 

[Basil]

Tony,
really looking forward to your next book publication.

 

[Tony Williams]

really looking forward to your next book publication.

Thanks. So am I!

 

[Wurger]

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;
165 kg weight.

Rheinmetall 3 cm M44 data:

400-420 rpm;
lenght as Mauser`s;
180 kg gun weight, 240 kg mount, combat weight 600 kg;
360º rotation, -10/+75º elevation;
Ammo same as Mauser`s.

A Mauser document states that Rheinmetall relocated develoment of 3 cm swivel mounts for E-boats to the Brünner Waffenfabrik, as well as the U-boat (Type XXI) double mount to the Czech company Bata, at Zlin. Preliminary work was probably undertaken by Rh (my guess). Rheinmetall was also designing a triaxial single mount for the M44, as well as a quadruple mount.

 

[Wurger]

As for the 2.8cm, I have no idea. Kind of reminds me of the squeezebore 2.8cm PaK though.

Yes, there was an automatic aircraft gun which fired 2.8/2cm squeezebore ammo, although the cartridge case was different from the army manually-loaded gun.

My impression is that denomination does not correspond with "Geraet" number, as so many examples show, making these two developments different ones. The 28mm caliber, non squeeze bore, was used with the WBA L/52 light infantry gun, firing a 0,381 kg shell from a tripod, intended to attack gun positions and machine gun nests. It was a 1938 prototype, though, and a Heer project.

 

[Tony Williams]

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;
165 kg weight.

Rheinmetall 3 cm M44 data:

400-420 rpm;
lenght as Mauser`s;
180 kg gun weight, 240 kg mount, combat weight 600 kg;
360º rotation, -10/+75º elevation;
Ammo same as Mauser`s.

Thank you. I understand that the ammo was probably the same as the MK 303 (30 x 211).

Frank Petter's excellent book on WW2 German aircraft ammunition includes photos of the 28 x 216B ammunition used by the MK 411 motor cannon. Does that mean that the 30 mm MK 411 did not exist, and that the Gerät designation was wrong?

 

[Wurger]

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;
165 kg weight.

Rheinmetall 3 cm M44 data:

400-420 rpm;
lenght as Mauser`s;
180 kg gun weight, 240 kg mount, combat weight 600 kg;
360º rotation, -10/+75º elevation;
Ammo same as Mauser`s.

Thank you. I understand that the ammo was probably the same as the MK 303 (30 x 211).

Frank Petter's excellent book on WW2 German aircraft ammunition includes photos of the 28 x 216B ammunition used by the MK 411 motor cannon. Does that mean that the 30 mm MK 411 did not exist, and that the Gerät designation was wrong?

Not at all, the MK 411 did exist but, according my sources (who state it was a 30mm gun) , was rejected by the Luftwaffe. The Geraet number usually doesn't match the designation, but it could be that this one does. Can you post some of these ammo photos, Tony?

 

[Tony Williams]

Frank Petter's excellent book on WW2 German aircraft ammunition includes photos of the 28 x 216B ammunition used by the MK 411 motor cannon. Does that mean that the 30 mm MK 411 did not exist, and that the Gerät designation was wrong?

Further digging in Petter's book (somewhat slow due to the need to type the German text into a translator) reveals that the "Motorkanone MK 411" was designed in two calibres, 28 mm and 30 mm. The 28 x 216B round exists (a couple of examples in a collection) but the 30 mm is unknown.

Petter's designation for this project (both 28 mm and 30 mm) is MK 411, but when he specifically describes the 28 mm version he designates it Gerät 411.

Anyway, the MK 411 was clearly designed for aircraft use, as instead of being gas or recoil operated, the mechanism was driven by the aircraft engine as the Motorkanone designation indicates. The gun would have fired through the hollow propeller hub. Weight of a practice projectile was 300 g; MV not known. Both steel and brass-cased versions of the ammunition survive, both dated 1941.

 

[Wurger]

Frank Petter's excellent book on WW2 German aircraft ammunition includes photos of the 28 x 216B ammunition used by the MK 411 motor cannon. Does that mean that the 30 mm MK 411 did not exist, and that the Gerät designation was wrong?

Further digging in Petter's book (somewhat slow due to the need to type the German text into a translator) reveals that the "Motorkanone MK 411" was designed in two calibres, 28 mm and 30 mm. The 28 x 216B round exists (a couple of examples in a collection) but the 30 mm is unknown.

Petter's designation for this project (both 28 mm and 30 mm) is MK 411, but when he specifically describes the 28 mm version he designates it Gerät 411.

Anyway, the MK 411 was clearly designed for aircraft use, as instead of being gas or recoil operated, the mechanism was driven by the aircraft engine as the Motorkanone designation indicates. The gun would have fired through the hollow propeller hub. Weight of a practice projectile was 300 g; MV not known. Both steel and brass-cased versions of the ammunition survive, both dated 1941.

Great information, thanks. Does he mention Krupp's MK 413? It would be a 3 barreled motorkanone.

 

[Tony Williams]

Does he mention Krupp's MK 413? It would be a 3 barreled motorkanone.

No mention that I can see - the book is only concerned with ammunition, there is no index for the guns which are mentioned.

 

[Wurger]

Frank Petter's excellent book on WW2 German aircraft ammunition includes photos of the 28 x 216B ammunition used by the MK 411 motor cannon. Does that mean that the 30 mm MK 411 did not exist, and that the Gerät designation was wrong?

Further digging in Petter's book (somewhat slow due to the need to type the German text into a translator) reveals that the "Motorkanone MK 411" was designed in two calibres, 28 mm and 30 mm. The 28 x 216B round exists (a couple of examples in a collection) but the 30 mm is unknown.

Petter's designation for this project (both 28 mm and 30 mm) is MK 411, but when he specifically describes the 28 mm version he designates it Gerät 411.

Anyway, the MK 411 was clearly designed for aircraft use, as instead of being gas or recoil operated, the mechanism was driven by the aircraft engine as the Motorkanone designation indicates. The gun would have fired through the hollow propeller hub. Weight of a practice projectile was 300 g; MV not known. Both steel and brass-cased versions of the ammunition survive, both dated 1941.

I would love to see the 28x216B rounds. Does the book have the 34x148mm rounds by DWM? Where they intended for what weapon?

 

[Tony Williams]

Yes, he has photos and drawings of the 34 x 149. I actually have one of the cases for that, and have had a replica M-Geschoss projectile made. I have no idea what gun it was made for.

The brass-cased MK 411 is shown below. I hope Mr Petter doesn't mind me showing this. I must say that his book is superb - 900 pages on high-quality gloss paper and profusely illustrated. It is expensive, but a must-have for any serious student of this subject. The title is Munition für deutsche Flieger Bordwaffen bis 1945. He can be contacted at: Petter.Franz at t-online.de

 

[Wurger]

Thanks for sharing, Tony.

 

[Tony Williams]

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;

I have just realised that these ballistics are exactly correct for the 30 x 184B as used in the MK 103; the 30 x 211 was much more powerful.

 

[_Sarcasticat_]

the 3.7cm/57 Flak M43, the navalized 3.7cm Flak 37

Not quite. The standard Luftwaffe/Army 3,7 cm AA gun was designated the Flak 18, 36 or 37. The gun and ammo were identical, but the Flak 36 had a better mounting while the Flak 37 was fitted to use more advanced sights. They were never intended for fitting to ships (although some were).

The Flak M43 was a new design with a different operating system (but the same ammo), intended from the start to be the all-service AA gun.

On the naval side, they had the manually-loaded SK/C-30 guns firing much more powerful ammo. In the late 1930s the automatic SK/C-36 (Bofors copy) briefly emerged, with its own unique ammo. This was later developed into the Flak M42. The Flak M43 was intended to be the replacement, but it was all too late to make a difference.

I stated Flak 37, but I meant Flak 43.
They're very similar, if not the same.

 

[_Sarcasticat_]

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;
165 kg weight.

Rheinmetall 3 cm M44 data:

400-420 rpm;
lenght as Mauser`s;
180 kg gun weight, 240 kg mount, combat weight 600 kg;
360º rotation, -10/+75º elevation;
Ammo same as Mauser`s.

A Mauser document states that Rheinmetall relocated develoment of 3 cm swivel mounts for E-boats to the Brünner Waffenfabrik, as well as the U-boat (Type XXI) double mount to the Czech company Bata, at Zlin. Preliminary work was probably undertaken by Rh (my guess). Rheinmetall was also designing a triaxial single mount for the M44, as well as a quadruple mount.

Now this is what I like to see.
Though are there any sketches or drawings of the mounts? Particularly a shielded twin - perhaps intended for naval use?

 

[Wurger]

The twin shielded mount was envisaged for the 1942 and 1945 "Zerstörer" projects, as well as the "Kleinen Kriegszerstörer". Unfortunatelly I do not know any original sketch.

 

[Tony Williams]

I stated Flak 37, but I meant Flak 43.
They're very similar, if not the same.

They used the same ammunition, but were very different guns. The Flak 37 used the typical Rheinmetall pre-WW2 recoil-operated mechanism first introduced in the Flak 18, while the Flak 43 was gas operated, and had a mechanism based on the 30mm MK 103.

 

[_Sarcasticat_]

The twin shielded mount was envisaged for the 1942 and 1945 "Zerstörer" projects, as well as the "Kleinen Kriegszerstörer". Unfortunatelly I do not know any original sketch.

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

I stated Flak 37, but I meant Flak 43.
They're very similar, if not the same.

They used the same ammunition, but were very different guns. The Flak 37 used the typical Rheinmetall pre-WW2 recoil-operated mechanism first introduced in the Flak 18, while the Flak 43 was gas operated, and had a mechanism based on the 30mm MK 103.

I was referring to the Flak 43 and M43 specifically but this is something I did not know. Just goes to show I need to learn about anti-aircraft cannon operation.

 

[Tony Williams]

Just goes to show I need to learn about anti-aircraft cannon operation.

There's a new book out next year which could be of interest

 

[_Sarcasticat_]

Just goes to show I need to learn about anti-aircraft cannon operation.

There's a new book out next year which could be of interest

Hit me up with the title, I'm interested.

 

[Tony Williams]

Just goes to show I need to learn about anti-aircraft cannon operation.

There's a new book out next year which could be of interest

Hit me up with the title, I'm interested.

Autocannon: the History of Automatic Cannon and their Ammunition. To be published by the Crowood Press.

 

[_Sarcasticat_]

Sounds good, thanks.

 

[Wurger]

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

You`re right, although some sources state 3,7cm double mounts. Could you show, according the original plans, the M44 double mount with some detail?

 

[_Sarcasticat_]

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

You`re right, although some sources state 3,7cm double mounts. Could you show, according the original plans, the M44 double mount with some detail?

I can, but it will be a few hours. It's not particularly sharp either but should be more than sufficient.

 

[_Sarcasticat_]

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

You`re right, although some sources state 3,7cm double mounts. Could you show, according the original plans, the M44 double mount with some detail?

Well that turned out to be a little bit longer than I intended, but better late than never.

 

[Wurger]

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

You`re right, although some sources state 3,7cm double mounts. Could you show, according the original plans, the M44 double mount with some detail?

Well that turned out to be a little bit longer than I intended, but better late than never.

That`s fine to me, tahnks a lot! It`s always great to see even specs of original plans as I only have drawings by Harald Möller (closer to the master plans) or the highly enhanced (and excellent) ones by Jürgen Eichhardt. The mounts, unfortunatelly, are very sketchy, but they do show us the general appearance. The straight shielding should be much like the one on the double 3,7cm Flak 42.

 

[_Sarcasticat_]

You're also forgetting the Flottentorpedoboote 1944, of which I have the plans. Bundesarchiv is a wonderful place.

You`re right, although some sources state 3,7cm double mounts. Could you show, according the original plans, the M44 double mount with some detail?

Well that turned out to be a little bit longer than I intended, but better late than never.

That`s fine to me, tahnks a lot! It`s always great to see even specs of original plans as I only have drawings by Harald Möller (closer to the master plans) or the highly enhanced (and excellent) ones by Jürgen Eichhardt. The mounts, unfortunatelly, are very sketchy, but they do show us the general appearance. The straight shielding should be much like the one on the double 3,7cm Flak 42.

Oh, I know if Möller. He's responsible for several sketches in Z-Vor! and Die Deutschen Flottentorpedoboote 1942-1945. Though I don't know who Eichhardt is. Maybe we can trade some plans and drawings at some time, I'm looking for a wide variety of things CL-sized and smaller that you might have. In response, I have a very large selection of things from the BDA.
The plain appearance of the 3cm is surprising given the detail of the rest of the plan. Well, maybe not so if you consider the mount and weapon not fully developed at the time. It appears that the shielding is slightly more extensive vertically than the 3.7cm/69 and at a strangle sharp angle. Oh well, it is what it is.

 

[Wurger]

I have both Harnacks`s and Fock`s books. Jürgen Eichhardt authored all those brilliant drawings in the second volume of Z-Vor!

 

[_Sarcasticat_]

I have been doing a bit more digging, since I'd like to sort this out for myself! I have copies of the Unterlüß reports as well as Musgrave and have found more information, but there is little data and some of it is confusing.

Musgrave states on page 198 (1992 edition) that the "3cm Flak 44" was by Rheinmetall, but on page 566 includes a "3cm Flak M.44" in a list of Mauser projects.

There are three relevant Unterlüß documents, listing the guns, the ammunition and the mountings.

The gun document includes the following 3 cm projects (among others):
MK 411 (engine-driven, 900 m/s)
Mk 303 (Brünner Waffenwerke); 400 rpm; 185 kg; 1,060 m/s; gas operated; naval Flak for U-Boote and S-Boote.
3 cm Flak M 44 (300M); Mauser project; gas operated; 400 rpm; 100 kg; 920 m/s.
3 cm Flak 4M 44 (I think - I only have a poor quality photocopy); Rheinmetall-Borsig (competitor for the above); 420 rpm; 140 kg; 920 m/s.

The ammunition document includes:
3 cm MK 411 HE-T; 440 g; 900 m/s
3 cm MK 303 (Br); M-Geschoss 330 g (72 g HE); 1100 m/s

The mounting document includes:
3 cm Flak M 44 twin mounting for S-Boote; 690 kg.

One curiosity is that I have the following note:

"2,8 cm Gerät 411: 28 x 216B ammunition.

A Krupp project initiated in 1941 for a motor cannon driven by the aircraft engine, and therefore presumably limited to use with vee-engines, with the gun fitting between the cylinder banks and firing through a hollow propeller hub. This used a large and powerful cartridge, but was unsuccessful. It is sometimes confused with the 3 cm MK 411, about which virtually nothing seems to be known except the calibre."

So - how does the 2,8 cm Gerät 411 match up with the 3 cm MK 411???

Mauser 3 cm Flak M44 data:

400 rpm, rotating bolt (schwenkverschluss?);
2,5 m gun lenght (1,6 m barrel);
forward cartridge ejection;
friction muzzle brake;
900-920 m/sec muzzle speed (with mine shell), 800 with HE, 725 with PzG;
Shell weights: Mine shell, 0,33 kg/ HE shell, 0,44 kg/ PzG 0,5 kg;
165 kg weight.

Rheinmetall 3 cm M44 data:

400-420 rpm;
lenght as Mauser`s;
180 kg gun weight, 240 kg mount, combat weight 600 kg;
360º rotation, -10/+75º elevation;
Ammo same as Mauser`s.

A Mauser document states that Rheinmetall relocated develoment of 3 cm swivel mounts for E-boats to the Brünner Waffenfabrik, as well as the U-boat (Type XXI) double mount to the Czech company Bata, at Zlin. Preliminary work was probably undertaken by Rh (my guess). Rheinmetall was also designing a triaxial single mount for the M44, as well as a quadruple mount.

Tony, Wurger,

I haven't forgotten or given up on my research - and I should thank you for the data provided about the 3cm/73 MK 303/Brunn/M44 - but it has shifted focus a little, and somewhat thankfully to a weapon with a little more information available.

So with the risk of necro-ing this thread, what data or sources could you both provide about the 3cm/44 MK 103? I did find a fountain of information on deutscheluftwaffe.de, but the website is now defunct and the links to the documents provided on the site are no longer available.
I did find some information on Waffen-Revue 93-96, but I would like to have more primary documents and detailed information in the same manner as what you guys provided for the 3cm/73. If you could take the time to do so, I would be forever grateful.