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WWII French 37mm sub-calibre anti-tank ammo for the SA-18


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#1 supertsar

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Posted 01 June 2011 - 1537 PM

Apparently the French produced a sub-calibre round (called a 37-37?) for their ubiquitous 37mm SA18 guns (Renault FT/R35/H35 etc). However I can find almost no info on it (how many were produced? was it used in combat? penetration? etc). Is anyone familiar with this round or know of a good book/site that might have some info on it? I am stumped!
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#2 Colin

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Posted 01 June 2011 - 1618 PM

Not aware of it, but did recently come across a picture of the 37mm trench gun being used as a sub-calibre device for the 1897 75mm howitizer, with the gun mounted on top.
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#3 supertsar

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Posted 01 June 2011 - 1650 PM

Maybe I wasn't clear on what I meant by "subcalibre" - maybe APCR is more appropriate. Here is a pic;

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Edited by supertsar, 01 June 2011 - 1652 PM.

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#4 Marek Tucan

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Posted 01 June 2011 - 1658 PM

It was APCR, however I wonder why they took the effort... Its effectiveness was only marginal.

EDIT: Was it intended for L/33 guns as well?

The core looks like it might be ca. 25mm - maybe 25mm AP shot taken from 25mm guns?

Edited by Tuccy, 01 June 2011 - 1659 PM.

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#5 Mk 1

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Posted 01 June 2011 - 1811 PM

A couple years ago, one of our members from France (GdG?) described to me a 37mm APDS sub-caliber round he had found documented in the French national archives while doing research for the game WW2 OnLine.

The round that is pictured, though, does appear pretty clearly to be APCR rather than APDS. So I wonder if he was describing the same round, or yet another sub-caliber round.

As I recall he said it managed to boost the performance to a level that was competitive with the French 25mm AT gun. I would be surprised if they achieved that with the L21 barrel of the SA18, though. My guess is that it would have needed the L33 barrel to get anywhere near that performance.

He said the docs he had seen indicated it was just entering production when the armistice came. He had not found any documentation indicating it had actually been issued for service.

-Mark 1

Edited by Mk 1, 01 June 2011 - 1814 PM.

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#6 Tony Williams

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Posted 02 June 2011 - 0100 AM

Yes, the French 37mm ammo to see service was APCR not APDS. There were some variations, but the ones I know about had a hardened steel core inside a magnesium body (which provided flash and incendiary effects on impact). The pic below shows the 37x94R Mle 1935 in my collection - almost certainly with a replica magnesium body, because the real thing tends to deteriorate rapidly. Projectile weight was 390g and MV 600 m/s (compare with standard APHE which weighed 500g and was fired at 388 m/s). Penetration is quoted at 25mm/30 degrees/100m, or 19mm/30 degrees/500m (Guns v Armour site).

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APDS was a French invention (Brandt IIRC) just before WW2, but they had no time to introduce it into service. The work was transferred to Canada early in the war, and from there to the UK.
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#7 supertsar

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Posted 02 June 2011 - 1628 PM

Wow thanks Tony and Mk 1.
This is pretty amazing if I am drawing the correct conclusion - the mle 1935 was actually an APCR round, not an APC/APCBC as is stated everywhere (including the guns vs armor website).
If this is the case I am really impressed with France's ingenuity when it came to updating their equipment without spending lots of money. Thats quite an improvement over their old mle24 AP projectile. They probably went back to the APCBC design for their mle38 L/33 due to cost.

Man, 65+ years after WWII and still no good book on French AFVs in English that sorts all this out....
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#8 TonyE

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Posted 02 June 2011 - 1844 PM

A couple years ago, one of our members from France (GdG?) described to me a 37mm APDS sub-caliber round he had found documented in the French national archives while doing research for the game WW2 OnLine.


The book France 1940 by Ferrard has a few pages about this.
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#9 Mk 1

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Posted 03 June 2011 - 1252 PM

The book France 1940 by Ferrard has a few pages about this.

About what?

About the APCR round? Any information on its service, or scale of issue? Of particular interest to me ... was the round issued widely enough to make it to the overseas garrisons (lots of R35s in French North Africa and the Levant), and was the round issued for the 37mm infantry gun too (still the front line AT defense of garissons that didn't receive their allocation of 25mm AT guns)?

Or rather, were you saying it contains further reference to the "mystery" APDS round?

-Mark 1
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#10 TonyE

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Posted 04 June 2011 - 1636 PM

About what?

About the APCR round? Any information on its service, or scale of issue? Of particular interest to me ... was the round issued widely enough to make it to the overseas garrisons (lots of R35s in French North Africa and the Levant), and was the round issued for the 37mm infantry gun too (still the front line AT defense of garissons that didn't receive their allocation of 25mm AT guns)?

Or rather, were you saying it contains further reference to the "mystery" APDS round?

-Mark 1


Mark1

From what i understand the APCR round (Obus Rupture mle.1935 and mle.37) was the standard shell of the 37mm SA18 armed light tanks in 1940. Please do note however that it was only used by those that had received the "modifié 1937" upgrades to the short 37mm gun, which enabled the gun to fire this round. This would be the Hotchkiss, FCM and Renault R35 tanks, most of which would have been built after the introduction of this modification anyway.

The infantry gun (37mm mle.16) could not fire this round though, it used the older types.

The "mystery" sub-caliber round was called 37/25mm and is said to have about the same penetration capacity as the 25mm ATG, with mv of 850m/s. But as far as i know it was not in use or in production before France fell. It would have been made available to all short 37mm guns.



Tucs,
While the epitome of Tanknet potency is big guns and high penetration, in 1940 many german tanks only had around 15mm armour so every little extra mm of penetration would be helpfull. ;)
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#11 supertsar

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Posted 04 June 2011 - 1649 PM

Mark1

From what i understand the APCR round (Obus Rupture mle.1935 and mle.37) was the standard shell of the 37mm SA18 armed light tanks in 1940. Please do note however that it was only used by those that had received the "modifié 1937" upgrades to the short 37mm gun, which enabled the gun to fire this round. This would be the Hotchkiss, FCM and Renault R35 tanks, most of which would have been built after the introduction of this modification anyway.

The infantry gun (37mm mle.16) could not fire this round though, it used the older types.

The "mystery" sub-caliber round was called 37/25mm and is said to have about the same penetration capacity as the 25mm ATG, with mv of 850m/s. But as far as i know it was not in use or in production before France fell. It would have been made available to all short 37mm guns.



Tucs,
While the epitome of Tanknet potency is big guns and high penetration, in 1940 many german tanks only had around 15mm armour so every little extra mm of penetration would be helpfull. ;)



Just so I am clear - the round pictured in the 3rd post is the "APCR round Obus Rupture mle.1935 and mle.37)" correct?

Do you know what would have prevented it from being fired in the older (Renault FT) 37mm SA18s? I believe the casings are the same lengths (37x94) so it should seat correctly in the chamber....

Edited by supertsar, 04 June 2011 - 1715 PM.

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#12 Tony Williams

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Posted 05 June 2011 - 0431 AM

The "mystery" sub-caliber round was called 37/25mm and is said to have about the same penetration capacity as the 25mm ATG, with mv of 850m/s. But as far as i know it was not in use or in production before France fell. It would have been made available to all short 37mm guns.

I find that hard to believe, looking at the propellant capacities of the cases. Now I could believe it of the 37mm Mle 1938 gun, which had a much bigger cartridge case. See pics below, from the Ammo Photo Gallery on my website:

Posted Image
7.92x57 (MG 34/42, Besa), 12.7x81 (0.5" Vickers), 13.9x99B (.55" Boys), 15x104 (Besa), 20x99R (ShVAK), 20x138B (KwK 30/38), 25x194R (French Hotchkiss), 37x94R (French Mle 1916/1918)

Posted Image
37x94R (French 37mm Mle 1916/1918), 37x149R (French 37mm Mle 1938), 37x249R (German 3,7cm), 37x257R (Polish wz 36 - 37mm Bofors), 37x268R (Czech 37mm vz 34/38), 40x304R (British 2pdr), 47x195R (Italian 47mm Mod 37 - Austrian Bohler), 45 x 310R (Russian Mod 37), 47x193R French 47mm Mle 1935
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#13 scotsman

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Posted 06 June 2011 - 1355 PM

Hey Gang...

I actually have a round of this ammo in my collection...my cap is of the same form as in the superstar picture in that it fully encloses the penetrator. It is not a partial cap as in Tony's example (agreee with his assessment though that his cap is likely a remanufacture and not original). I also have two battlefield recovered shots minus their cap, so someone was popping them off...I got the battlefield recoveries long before I was able to locate a complete round of the ammunition. I'll try and post a picture or two later...

To be honest, I'm not sure my cap isn't a remanufacture as well, its a simple cap that screws to the base and doesnt have any internal shoulders to hold the penetrator if I remember...anyway more later!

Edited by scotsman, 06 June 2011 - 1400 PM.

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#14 supertsar

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Posted 06 June 2011 - 1711 PM

Hey Gang...

I actually have a round of this ammo in my collection...my cap is of the same form as in the superstar picture in that it fully encloses the penetrator. It is not a partial cap as in Tony's example (agreee with his assessment though that his cap is likely a remanufacture and not original). I also have two battlefield recovered shots minus their cap, so someone was popping them off...I got the battlefield recoveries long before I was able to locate a complete round of the ammunition. I'll try and post a picture or two later...

To be honest, I'm not sure my cap isn't a remanufacture as well, its a simple cap that screws to the base and doesnt have any internal shoulders to hold the penetrator if I remember...anyway more later!


Scotsman, is your casing marked "37-37" ????
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#15 scotsman

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Posted 09 June 2011 - 0855 AM

Yes - 1940 producion based on stampings...
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#16 Cdn Blackshirt

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Posted 09 June 2011 - 1149 AM

Tangent Question: Does anyone know why France didn't re-barrel their small calibre tank guns with something longer?

It now seems especially odd as they apparently understood greater penetration would be required and invested in more expensive ammunition.

???
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#17 TonyE

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Posted 09 June 2011 - 1354 PM

Tangent Question: Does anyone know why France didn't re-barrel their small calibre tank guns with something longer?

It now seems especially odd as they apparently understood greater penetration would be required and invested in more expensive ammunition.

???


They did, starting with a goal of giving platoon and company commander tanks the longer 37mm SA38 L/33 guns. Until there was enough guns to reequip all or most light tanks, souped-up ammo was the way to go for the rest.
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#18 Cdn Blackshirt

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Posted 09 June 2011 - 1419 PM

They did, starting with a goal of giving platoon and company commander tanks the longer 37mm SA38 L/33 guns. Until there was enough guns to reequip all or most light tanks, souped-up ammo was the way to go for the rest.


So it was primarily a matter of time then....they would've re-barrelled all if they had the opportunity?
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#19 Mk 1

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Posted 10 June 2011 - 0327 AM

So it was primarily a matter of time then....they would've re-barrelled all if they had the opportunity?

On one side you did indeed have time ... while on the other side you had cost, and industrial capacity that was not exactly at a peak.

They were building new model tanks, and new AT guns, new model fighter and bomber planes, new battleships and battlecruisers, and new model rifles. Amidst all of that, the upgunning of old tanks was somewhere in line on the priorities list, but maybe not at the very top.

At the same time millions of workers had been called up and were sitting in trenches doing nothing for the critical months between September of 1939 and the start of the actual fighting in the west in April (Norway). While the communists were organizing among the rest and leading slow-downs, strikes, and even workplace sabotage, because Comminterm had started railing against the war-mongering capitalist west (the Soviets had a non-aggression pact with Germany).

So yes, it was time ... and some other issues too.

-Mark 1
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#20 GdG**

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Posted 15 June 2011 - 1407 PM

Mk1, it may have been Pachy, who was more into ammunitions than I.

IIRC, this new ammunition was only issue in low quantités in 1940. There had no point on spending too much ressources on such an upgrade, since by the end of 1940 most of the short barreled 37 mm guns would have been replaced by the longer SA38, and that the SA18 was not meant for antitank use. In the mind of the staff it would have been more usefull in North Africa against Italy, where top notch equipment was not required.

The next generation of light tank (late 1940 ) would have been fitted with the much more powerful 47 mm SA35 gun, and medium tanks would have inherited from the 47 mm SA37 (same performances as the long german 50 mm) whereas the heavies were getting the 75 mm.The new 75 mm Mle 1940 ammunition was under production in June and was to be issued by september 1940. It would have given a second life to the 75 mm Mle 1897 which was still widely used: IIRC it penetrated 90 mm @ 1000 m @ 30°.

Brandt was indeed ahead of its time and had been working on such ammunitions since the early 30's. IIRC he started with subcalibered 203 mm naval ammunitions and he later felt that with the huge stocks left from ww1, there would have a juicy market. They as well paved the way for the bazooka. By the end of June he was allowed to give all his data to Canada so that it wouldn't end in German hands.
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