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20mm. Guns Of WW2.

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Panzergranate_ #1 Posted 29 November 2012 - 11:52 PM

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When some folks think of 20mm. guns their minds immediately think of glorified machineguns or BB guns, peashooters, etc.

I collect range test data from all participants in WW2, 90% of it hasn't been published or online yet, so I've decided to share some of it on here....

Britain.

20mm. L.110.5. 1 Pounder Oerlikon Anti-Tank Gun.

This was Britain's first anti-tank gun and entered service in 1937 as a stop gap whilst the 2 Pounder was delayed due to ammunition problems. The weapon was mounted on tracks and towed behind Carden-Loyd tracked carriers. It saw action in Norway and France in 1940. Many German propoganda pictures of the Dunkirk beaches show them amongst the abandoned equipment.

(British figures) Versus vertical FHRHA with AP-T:

62mm. @ 100 yards.
42mm. @ 500 yards.
28mm. @ 1,000 yards.

20mm. L.72.4. Polsten Automatic Cannon.

This was a licenced copy of the 20mm. Swiss Oerlikon automatic cannon.

(British Figures) Versus vertical FHRHA with AP-I:

40mm. @ 100 yards.
27mm. @ 500 yards.
18mm. @ 1,000 yards.

20mm. L.85.1. Hispano-Suiza Automatic Cannon.

This was the armament of the Humber.III. armoured car (not known to have seen active service) and proposed armament upgrade for what have been the Vickers Light Tank Mark.VI.D. in 1941. This was a modified aircraft cannon with AP ammo (not normally used by aircraft) especially developed for it. Conventional aircraft HE-frag and HE-I would have also been available.

(British Figures) Versus FHRHA with AP-T:

47mm. @ 100 yards.
32mm. @ 500 yards.
21mm. @ 1,000 yards.

Panzergranate_ #2 Posted 30 November 2012 - 12:29 AM

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Germany.

20mm. L.55. KwK.30. and KwK.38. Tank Gun.

The KwK.30. gun was developed before Germany had restarted tank development and originated on armoured cars. More familiar as the armament of the Pz.II. light tank. It was semi-automatic in action. The KwK.38. was a fully automatic version that shared components from the FlaK.38. anti-aircraft gun. The KwK.38. was used on the SdKfz.222., SdKfz.231., SdKfz.232., SdKfz.233/1. and SdKfz.234/1. armoured cars. Other ammunition used was HE-frag.

(German figures) Versus vertical FHRHA with PzGr.30. AP:

31mm. @ 100 metres.
21mm. @ 500 metres.
14mm. @ 1,000 metres.

(German figures) Versus vertical FHRHA with PzGr.39. APCBC-HE (Note that the tail grenade charge filling differed from normal and was a blue incendary explosive gel):

40mm. @ 100 metres.
31mm. @ 500 metres.

(German figures) Versus vertical FHRHA with PzGr.40. APCR:

52mm. @ 100 metres.

20mm. L.112..5. FlaK.30. / FlaK.38. Anti-Aircraft Gun.

This gun was capable of firing all the same ammunition as the 20mm. L.55. KwK.30. and KwK.38. Officially only PzGr.30. was issued but stories exist of armoured car units exchanging PzGr.39. and PzGr.40. ammunition for HE-I shells. Other ammunition was HE-Frag and HE-I.

During the Battle Of France some SdKfz.222. had their KwK.38. main gun and co-axial machine gun removed and replaced with FlaK.30. anti-aircraft guns in order to increase anti-tank firepower. This later led to a lot of misquotations as to armament in many books and wargames rules. Many pictures of these conversions exist.

(German Figures) Versus vertical FHRHA with PzGr.30. AP:

57mm. @ 100 metres.
33mm. @ 500 metres.

Panzergranate_ #3 Posted 30 November 2012 - 12:41 AM

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Russia.

20mm. L.107. TnSH. Automatic Cannon.

This high velocity version of the ShVaK 20mm. automatic cannon has a longer barrel and was used in the T-60 light tank. The rate of fire is slower than the aircraft ShVak cannon.

(German figures) Versus vertical FHRHA with APHE (Note that the weak propellant is gunpowder with nitro-celluose primer):

27mm. @ 100 metres.
22mm. @ 500 metres.
20mm. @1,000 metres.

(German figure) Versus vertical FHRHA with HVAP:

60mm. @ 100 metres.
40mm. @ 500 metres.
27mm. @ 1,000 metres.

StickyFinger #4 Posted 30 November 2012 - 12:42 AM

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Can you please give the sources for this information, thanks

Panzergranate_ #5 Posted 30 November 2012 - 12:54 AM

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Italy.

20mm. L.65. Breda Automatic Cannon.

This gun was intended as an anti-aircraft weapon but was mounted on all manner of vehicles by the Italians, Germans and British during the North African campaign. During the Spanish Civil War facist forces modified the turrets of a number of Panzer.I.A. tanks to take the gun. Many pictures of these tanks exist.

(German figures) Versus vertcal FHRHA with AP:

36mm. @ 100 metres.
24mm. @ 500 metres.
16mm. @ 1,000 metres.

20mm. L.77. Scotti Automatic Cannon.

This weapon was used as both a tank gun and light anti-tank gun by the Italian forces in North Africa. Again uses by all sides and bodged onto all manner of vehicles.

(German figures) Versus vertical FHRHA with AP:

43mm. @ 100 metres.
29mm. @ 500 metres.
19mm. @ 1,000 metres.

Fiold #6 Posted 30 November 2012 - 12:57 AM

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Polish 20 mm FK wz. 38 cannon. Probably the best of prewar 20 mm guns.
Ammunition - Polish made 20x140 or Solothurn 20x138B (gun was capable to fire both).
Penetration
Against normal armor
40 mm at 200 meters and 0 degrees
Against carburised armor
20 mm at 300 meters and 0 degrees
Muzzle velocity - 850 m/s or more

Panzergranate_ #7 Posted 30 November 2012 - 01:20 AM

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View PostFiold, on 30 November 2012 - 12:57 AM, said:

Polish 20 mm FK wz. 38 cannon. Probably the best of prewar 20 mm guns.
Ammunition - Polish made 20x140 or Solothurn 20x138B (gun was capable to fire both).
Penetration
Against normal armor
40 mm at 200 meters and 0 degrees
Against carburised armor
20 mm at 300 meters and 0 degrees
Muzzle velocity - 850 m/s or more


Poland.

20mm. L.74. NkM. Automatic Cannon.

(German Figures) Versus FHRHA with AP:

42mm. @ 100 metres.

Panzergranate_ #8 Posted 30 November 2012 - 01:55 AM

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View PostStickyFinger, on 30 November 2012 - 12:42 AM, said:

Can you please give the sources for this information, thanks

Notes that I took back in 1986 - 1987 of declassified and translated files and reports from the Rhienmetall-Borstig test facility, Kummersdorf.

Those reliably methodical Germans were extremely good at testing everything that they produced, their friends produced and that they captured.

The archives were secured by the Allies in 1945, whisked away and translated. Because of the wealth of gunnery performance data of Soviet anti-tank weapons, it was classified (most secret) It remained secret until sometime in the 1960's or 1970's.

Some incomplete snippets have leaked out, mainly on the popular primary German guns with basic well known ammo types and other unimportant items that have been declassified as quite a few copies of the original and translated data exist plus the original personnel who ran the tests and compiled the data back during WW2.

However the Soviet data, German PzGr.44. FSAPDS range test data and reports, wire guided weapons and stuff NATO would rather our Commie cousins didn't know that we had remained under tabs.

The archive I came across was during the moving of the old library and archive, at the Bovington Tank Musem in 1986 - 1987, to the then new libary and archive. The museum has had boxes of declassified drawing, intelligence reports, training manuals, etc. donated to it for decades so this was a chance find.

I took notes of scraps of paper, notebooks, etc. during my hour long lunch breaks. I've spent years number crunching it and using it for wargames rules.

For instance in one report a British Major, whilst walking across the former site of an intense tank battle days earlier (North west Germany during the first week of February1945), spotted a strange looking dart shaped object with metal fins sticking out of the ground. (It was the first time the Allies had ever seen a German FSAPDS projectile). Subsequent searching found the discarded sabot components and it was determined to have been fired from an 88mm. gun.

There are some gems....

From a German analysis on captured Soviet tanks in 1942:

The underside of a T-34's sponsons is unarmoured and very thin. Placing an explosive charge under here will breakthrough the metal and ignite the shells stored on clips directly above. (Unfortunately the same problem existed for all versions of the Lee, Grant and Sherman too and the Germans were aware....)

The underside of the rear turret overhang of a KV-1 (they meant KV-1 model 1940, KV-1A, KV-1B and KV-1E) is very thinly armoured and can be forced open with a well placed explosive charge. (Note that the Russians revised the turret overhang design on the KV-1C to prevent this).

All this information was passed to troops at the front via the German Army's "Signal" propoganda magazine.

Out of interest, who wants to know what the WW2 Soviet guns REALLY did regarding armour penetration??

Walker28361 #9 Posted 30 November 2012 - 02:43 AM

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Fascinating details, personally I'd love to read more, it would make a good starting point for my own research - I'm trying to put some small scale miniatures rules together. :Smile_great:

Panzergranate_ #10 Posted 30 November 2012 - 03:20 AM

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View PostWalker28361, on 30 November 2012 - 02:43 AM, said:

Fascinating details, personally I'd love to read more, it would make a good starting point for my own research - I'm trying to put some small scale miniatures rules together. :Smile_great:

I spent a couple of years with the rules that my WW2 group played at the South Dorset Millitary Society and at conventions perfecting infantry versus tanks without ranged anti-tank weapons.... or to put it another way, running up to an enemy tank, boarding and destroying or disabling it by some other means.

I based a lot on German and Finnish training and historical accounts plus reports. Fortunately Squadron Signal books had a lot of pictures of knocked out Soviet KV's with troops still in the process of mopping up, complete with the caption of what had just happened and how.

Folks wanted to recreate this in the rules and after a few rewrites and amendments, I had something that worked fine and prototypically enough that mimicked real life actions.

General weapons used by German tank boarders were:

Gebaltledung (7 headed grenade), satchel charge, mines or rags soaked in grease or oil, etc.

The first problem is boarding a tank, especially if it is moving. Next is surviving the tank's crew (or other tanks) trying to remove the boarder(s). Then there is choice of attack. Opening the hatch, Hollywood style, and throwing in a grenade doesn't work in reality as the crew can simply lock the hatches shut from inside.

Normal choice of attack is turret overhang or simply open the engine covers (tools such as pry bars are conviently carried on the decks of most tanks), throwing in a grenade, molotov or, much better, burning grease and oil soaked rags to damage hoses and wires to disable the engine. In the case of burning rags smoke and fumes will enter fighting compartment via ventilators, forcing the crew to open a hatch for air.... a grenade or submachinegun pushed into the opening will sort out the panicked crew.

The Germans issued various grades of badges to troops who destroyed or disabled an enemy tank through boarding and other direct improvised actions.

Another German (and Finnish) trick was to quickly attach a wire to the tank's antenna and the hull (grounding the antenna prevents the polarised electromagnetic field being generated from which the radio waves eminate) thus preventing the tank from radioing for help.

OK converting this into dice throws, rules and stages with possible random outcomes is not easy, but it is attention to details and actions, such as this that make some skirmish and larger action wargames rules enjoyable.

Walker28361 #11 Posted 30 November 2012 - 09:07 AM

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Thank you, this is all good stuff. Specific to your reply do you have any details regarding the Klorihaartsi (I think) grenades used by the Finns? I'm afraid my web-searching technique isn't that great!

Fiold #12 Posted 01 December 2012 - 10:35 AM

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View PostPanzergranate_, on 30 November 2012 - 01:20 AM, said:

Poland.

20mm. L.74. NkM. Automatic Cannon.

(German Figures) Versus FHRHA with AP:

42mm. @ 100 metres.

Do you know which ammo was used during these tests? German one (20x138B) or Polish (20x140)?

Panzergranate_ #13 Posted 01 December 2012 - 11:27 PM

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View PostFiold, on 01 December 2012 - 10:35 AM, said:

Do you know which ammo was used during these tests? German one (20x138B) or Polish (20x140)?

I suspect German ammo as most of the captured weapons evaluations were to access worthyness for service with Germans force or Axis allies, either directly or with modification.

The Germans converted many unused French and used Polish 75mm. L.36.3. Puteaux field guns into the PaK.97/38. and PaK.97/40. for use by the Germans, Bulgarians, Romanians and Hungarians. They also sold some to Finland.

However the Germans did not use Polish APHE ammunition (for twisted Nazi Ideological reasons) and transfered all stocks to the Bulgarians, Hungarians and Romanians. The Fins produced their own ammunition for the gun.  

The Polish Army's 14mm. Radom anti-tank rifles were given to the Italians.

The 20mm. NkN were the guns manned by Polish school children (ages 10 to 14) during the historically glossed over coincidental Soviet invasion of Poland in 1939. A Soviet BT-5 was amongst one of the "kills" that was riddled with 20mm. cannon shells whilst attempting to ford the shallow river under the road bridge that the children were defending.

They held out for a day until overrun and captured by Russian infantry. All the children were executed.

Fiold #14 Posted 02 December 2012 - 01:30 PM

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View PostPanzergranate_, on 01 December 2012 - 11:27 PM, said:


The Polish Army's 14mm. Radom anti-tank rifles were given to the Italians.


Poland didn't have 14 mm AT rifles. These Radom AT rifles were wz. 35 UR 7,92 mm.
http://en.wikipedia....anti-tank_rifle


View PostPanzergranate_, on 01 December 2012 - 11:27 PM, said:

The 20mm. NkN were the guns manned by Polish school children (ages 10 to 14) during the historically glossed over coincidental Soviet invasion of Poland in 1939. A Soviet BT-5 was amongst one of the "kills" that was riddled with 20mm. cannon shells whilst attempting to ford the shallow river under the road bridge that the children were defending.

They held out for a day until overrun and captured by Russian infantry. All the children were executed.

I strongly doubt that story. Wz. 38 NKMs were very modern and just 59 of them were produced. 26 were delivered to tanks factories and 23 or 24 were mounted in TKS tankettes and 1 or 2 in TK-3 tankettes. I doubt if children would be allowed to use such modern and rare guns.

Panzergranate_ #15 Posted 02 December 2012 - 05:29 PM

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The story is online and in books. It is an historical event.

The school children took over the gun Polish Army positions after finding them abandoned in the morning, the original gun crews having deserted their posts during the night, and defended the large stone bridge in the middle of the town using the two 20mm. light AA gun emplacements overlooking the bridge on the embankment.

Unless the Polish Army also used the only other 20mm. AA guns that wasn't made by the Germans, the Danish 20mm. L.60. Madsen, then the guns described must have been both NkM.