German 75mmL43, L48 and L46 velocities

[Mobius]

I don't agree with that second figure. I found that it was 2.5 kg as shown here:


found here:
http://www.lexpev.nl/downloads/h.dv.48158.pdf

[Boozername]

I can't post links or pics it seems.

But, it seems that 2.5 Kg (I have seen 2.51 Kg also), is a late war model. That info you posted is from Oct. 44. If anything, 2.43 (or 2.41Kg) is an earlier model. I can not see the Germans reducing the charge past Oct 44???? If anything, it seems the Germans increased the charge to 2.5 Kg.

So, is there any data of a higher charge that was initially reduced? Perhaps it was 2.5 Kg and was reduced to 2.43 Kg and then when things were worked out, they increased it back?

[Boozername]

October 44 report at Lone Sentry...

"A.P.C.B.C. May Become Most-Used German Pak 40 Ammunition" from Tactical and Technical Trends
An intelligence report on German Pak 40 antitank ammunition in WWII, from Tactical and Technical Trends, No. 51, October 1944.
[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]

A.P.C.B.C. MAY BECOME MOST-USED GERMAN PAK 40 AMMUNITION
German abandonment of the use of hollow-charge projectiles and AP 40 tungsten carbide core ammunition for the 75-mm antitank gun Pak 40 is indicated by reports from United States observers in the field. This, it is expected, will be followed by adoption, as the most common type of ammunition. of the 14.96-pound armor-piercing capped ballistic cap (A.P.C.B.C.) with a muzzle velocity of 2,600 f/s and the 12.5-pound high explosive with a muzzle velocity of 1,800 f/s.

General characteristics of the 75-mm German antitank gun Pak 40 are: Weight in action, 3,040 pounds; barrel length, 126.14 inches without muzzle brake, and 145.75 inches with muzzle brake; ground clearance, 13.8 inches; height of shield, 48.6 inches; diameter of wheels, 35.43 inches; elevation, -5° to +22°; traverse, 65°.

The welded tubular trails of the weapon are frequently found on medium-caliber German guns manufactured or modified within the last 18 months. The gun shield is a new design of two 4-mm spaced plates and is probably proof against small arms up to, but not including, 20-mm armor-piercing ammunition. Hand or semiautomatic operation is provided.

Previous references to this weapon were published in TACTICAL AND TECHNICAL TRENDS. No. 18, page 4 and No. 25, page 9.

[Boozername]

Handbook of Enemy Ammunition: Italian Fuzes, Gaines, Shell, etc., Shell ...
By The War Office, 1943

This document shows the PAK40 powder being 2.75 Kg. Interestingly enough, the KWK40 cartridge is just 2.16 Kg. The explanation for this, not known apparently to the authors, is that it is a 'Fur Trop' ammunition example. I had suggested this previously, that initial examples of captured guns/ammo might be from North Africa and Sicily and had tropical ammunition. Firing one of these ammunition rounds in a cold test environment would certainly skew the results.

I will post a link and screenshot when I can

[Mobius]

This is from "German Explosive Ordinance TM 9-1985-3 (Projectiles and Projectile Fuses)"
Departments of the Army and the Air Force March 1953.
It seems not to be complete.

5.35 lbs = 2.4267 kg. So this might be where the value comes from.

[Boozername]

That also looks like a Navy Report. I guess they copied.

I have seen shell casing marking that are in that lower range. The artificial silk 'sacks' that held the propellant, also had info including date of manufacture (month)

[Mobius]

Just to throw more confusion into the ring I found another shot of the PaK 40 round in "German Anti-Tank (Panzerjager) Troops in World War II" by Wolfgang Fleischer & Richard Eiermann - image on the right. The image on the left is from the above mentioned Pak 40 PDF.
What is strange is that the date of manufacture appears to be the same while the right fill is 2.75 kg while the left is 2.690 kg. (It looks like a "6" though it might be a "5").

[Boozername]

I believe that is also in your post 23 in this thread? I think that there is a mistake in that the AP40 has the same powderweight as the AP39. It looks hand drawn by the way.

Most sources say that the powder weight on the Pak40 AP39 is 2.75 Kg. It's about the same as a 88mm Tiger I AP39.

[Boozername]

The 'powder bag', that is the silk bag that is inside the cartridge that holds the powder, also has info printed on it. As an example, a 75mmL48 bag...

7.5 cm StuK 40
7.5cm KWK 40
2.51 Kg
Digl RP....etc
ktz 1943/27
Son 23.6.44

This calls out the ammo as used in 75mmL48 tank and assault guns, powder weight, powder type,
powder manufacture date, and manufacturer code and finally the manufacture date. Noteworthy is the nearly a year between powder manufacture and the shell being made.

I can edit in a picture when I am allowed to.

[Mobius]

From Spielberger's Sturmgeschutz book.
This is 1942 charge. So as we suspected the 2.43 kg. charge is the early version.

[Boozername]

That date would indicate a very early pzgr 39. In other words, it would be used by the initial batch of StuGs with the L43 barrel. It would be nice to find the Merkblatt that goes with it. I think the only one we have seen is the Oct 44 Merkblatt that calls out 2.5 Kg powder. I am thinking that the 2.5 Kg is the MAX load at this point. That is, stuffed as much as the internal space in the cartridge can take.

The early Merkblatt for the PAK40 is available and calls out the 2.75 Kg powder weight. I know of no source that calls out a lower charge.

I suspect the Stuk40/KWK40 story might be as follows...

Initial installation of L43 weapons occurred in spring 1942. Weapon trials were probably Fall/Winter 41. L43 barrels, like the L46 barrels in PAK40, had progressive twist. I suspect neither weapon had issues at this time. I believe the issue first reared its head with the StuG III F/8 mounting the first of the L48 barrels. Specifically, the first 400 that had not only the longer barrel, but also the progressive twist that the L43 and L46 had. This was changed to a uniform twist and I would assume all L48 tanks and assault guns/TD had the uniform twist barrel as standard equipment for the rest of the war. It would be interesting to know if Panzer IV ever had progressive twist L48 barrels or were they not installed.

The initial powder weight for the L43 weapon was 2.43 Kg. At the end of the war (Oct 44 Merkblatt), this weight was 2.5 Kg.

As for the reduction in powder weight between the initial 2.43 and 2.5 Kg values, it may have been an expedient to use the 'Fur Tropen' (2.16Kg) ammunition in the progressive twist L48 barrels (or just toss them and install uniform twist L48 barrels when available). To introduce a special reduced round for this situation is something that even the Germans wouldn't do.

As far as PAK40s ever reducing the charge, I really don't see any evidence besides hearsay. If anything, the weapon seemed to be a success from the start. Not many German AFV can say the same.

[Mobius]

There is ample evidence that there was at some time 750m/s reduced charge round. The story is not clear though.

[Elron Hubbub]

Can you share the ample evidence? Especially not second hand information? The story is not clear?

[Mobius]

I compiled enough to make a page on my web site.
http://www.panzer-war.com/page43.html

[Elron Hubbub]

Yes, it has second hand information. And, any, is too much. Ample does not make it any better.

[Mobius]

ORIGINAL: Elron Hubbub
Yes, it has second hand information. And, any, is too much. Ample does not make it any better.

Only if the information is lost or altered. You'd have to prove there is any. Even scans of orginal dattenbattens are still second hand so there is no way to post orginal information.

[Elron Hubbub]

Maybe we can take something from your page and ask you for your sources? Primary oe secondary? Or hearsay?

6. When the kannon 40 was introduced in April 1942 there was a shortage of ammunition for it. The new, stronger armor piercing shells Pz. Gr. 39 with a small cavity (17 gram explosive charge) were not available in sufficient numbers. What was available were armor piecing shells, the K. Gr rot Pz., used by the short 75mm cannon. These were fitted onto the large cartridge used in the Kannon 40. Some sources refer to this round as the model 38 with red band AP shell. Or, Pz. Gr. 38 rot, or even 7.5 Gr. Patr. 38 KwK confusing some people into thinking that there is an error and should be the HEAT shell Pz.Gr. 38 HL or Pz.Gr. 38 HL/A.

Please post what source you got this from?

[Elron Hubbub]

Archive Awareness: German experience in 1942
This website, which you cite, contradicts your theory. That is, it is from June 1942, it shows that the KWK 40 L43 (and StuK 40) were firing PzGr 39. There are no L48 weapons at this time. The actual number of KWK and StuK 40 weapons that were available in summer 1942 was actually very small. Your theory would then revolve around the inability to make the shorter cartridge cases. That would be incredible.

PAK 40 (which actually were fielded in greater numbers) would also be using the same projectile. Are you also saying that the PAK 40 had the same ammo (projectile) shortage? Do you really think the L24 projectile could handle the velocity at close ranges???

[Mobius]

ORIGINAL: Elron Hubbub

Archive Awareness: German experience in 1942
This website, which you cite, contradicts your theory. That is, it is from June 1942, it shows that the KWK 40 L43 (and StuK 40) were firing PzGr 39. There are no L48 weapons at this time. The actual number of KWK and StuK 40 weapons that were available in summer 1942 was actually very small. Your theory would then revolve around the inability to make the shorter cartridge cases. That would be incredible.

I'm not saying anything about the cartridges. I don't know what cartridges were being used.
Start with a 75mm ammo shortage.
"Their immediate distribution to the troops brought new problems, the first of which was the lack of ammunition. The Chief of Army Equipment and Commander of the Replacement Army, Generaloberst Frierdrich Fromm referred to the problem on May 1, 1942. For the heavy tank destroyer cannons promoted by the Army General Staff after the month of April there was only one kind of ammunition available and none at all for the 7.5 Tank Destroyer Cannon 41. ... An easing of the tense ammunition situation took place only in 1943." page 83-84
German Anti-Tank [Panzerjager] Troops in World War II by Wolfgang Fleischer & Richard Eiermann

[Mobius]

Add to this Russian report:

Report of the NKV Special Laboratory #101-1 on the topic of STUDY OF CHARACTERISTICS OF STRIKING A T-34 FUEL TANK WITH AP-HE OR CUMULATIVE (HEAT) SHELLS OF THE GERMAN FASCIST ARMY
Responsible: Rozov, Kaminskiy, Shurov
"The first test of the models happened on December 12th, 1943, from a 75 mm model 1940 ballistic cannon, from 30 meters. During these tests, the fuel tank was fully filled with diesel fuel, according to comrade Afonin's letter from December 5th.
8 model 38 shells were fired, as well as 5 model 39/40 shells, and 5 armor-burning (HEAT) shells."

When the fuel tank was hit by fragments of m.39/40 shell they were slowed abruptly. Many fragments did not penetrate.
Conclusions: 100% filled fuel tank of T-34 tank cannot be a source to inner explosion of T-34 tank, but even serves a protection from fragments of armor and cores of m.39/40 shells.

[report continues]

The effect of a detonation of a 75 mm AP shell with the red ring, equipped with 80 g of TNT and a 20 g detonator, is quite different. The explosive force grows several times over. The overtrack hull seams burst, and the roof of the model is deformed.
Conclusions:
The best ratio for detonation of T-34 fuel tank is when it's 10-15% full and AP shell m.38 bursting inside. Burst causes immediate detonation fuel's vapor which adds to shell's explosion, multiplying it by 2-4, which corresponds with effect of 105-122mm AP shell.

From "German Explosive Ordnance TM-9-1985-3 March 1953" K. Gr. rot Pz. Projectile; Black with red band. This is the projectile on the short 75mm AP. No other German 75mm AP is black with red ring.
From "Geschossringbush German ammo 1939" K. Gr. rot Pz. has a charge of 0.08 kg.
The complete shell seems to be identified as: 7,5 cm Pzgr. Patr. Kw.K
BTW, Pzgr 39 AP projectile only has 17 gram burster charge.