Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Contender » 11 May 2020 19:54

Yoozername wrote:
11 May 2020 05:17
Of course the Germans used the HL/C later on, and adopted sights that used it.
It is just plain economics...Making Pzgr 40, compared to simple HL/C. is a no-brainer ...in 1944-1945
Yes, however to avoid confusion I should point out the late sights still retained the Pzgr 40 scale & received the HEAT scale as an additional. I need to check but there maybe earlier sights with a HEAT scale also in tank reticles (for the /B if not for the A). I thought it was an interesting contrast considering the Sturmgeschütz III appears to lack these but the tank variation(s) do not and its not really something people regularly discuss or acknowledge.
Yoozername wrote:
11 May 2020 05:19
Yeah, never said they did. What is your point?
No you didn't that was not my implication I was only sharing what I have found to be the case relating to the aiming device.
Its too bad Mspaul is no longer active here as he would probably have more insight into AFV aiming devices.
Yoozername wrote:
11 May 2020 05:17
they had different weights....you didn't factor that?
Different speeds, different weights, different shapes, different aiming like I said it makes sense.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 12 May 2020 00:37

Contender wrote:
11 May 2020 19:54

Yes, however to avoid confusion I should point out the late sights still retained the Pzgr 40 scale & received the HEAT scale as an additional. I need to check but there maybe earlier sights with a HEAT scale also in tank reticles (for the /B if not for the A). I thought it was an interesting contrast considering the Sturmgeschütz III appears to lack these but the tank variation(s) do not and its not really something people regularly discuss or
We did have a discussion that I linked to.

viewtopic.php?t=236861

But tankers and StuGs (and other AFV using periscopic type sights), are different in that the reticle, and aiming is different. The tank sights were articulated and had the reticles that showed range, ammo type, and even weapon (MG). The reticle in the StuGs looked like this...

Image

As discussed, the optical periscope is attached to the range drum. So, the StuG gunner dials in the range on the corresponding ammo type as seen in the pic you posted. The tanker just keeps his eye on the telescopic sight. Of course, they both use elevation and traverse wheels.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Mobius » 12 May 2020 02:52

I do have the German ballistics of the 75mm HL and British ballistics 75mm APHE 43/CV 20 to compare. Both fired at an elevation of 1.4° the APHE shell will range 714 meters and the HL 856 meters.
75mm APCHL.jpg
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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by critical mass » 12 May 2020 17:09

Yoozername wrote:
11 May 2020 15:01
critical mass wrote:
11 May 2020 11:59
Penetration figures for HL are using a different definition than AP.
The rated penetration needed to be somewhat below actual holing performance in order to guarantee a behind target plate effect.
I suppose that one could test the hollow charge against a very thick plate to determine it's nominal penetration. But if one has some criteria for behind armor effects, one would test thinner plates till that criteria is satisfied. An example would be testing the HL/A against 12 cm plate, then a 10 cm plate, etc. I would like to see any real examples if you have them.
I have no source data to say how it was done in relation to the 7.5cm Hl Gr.38. However, I have data on how it was done on the schw. Gewehr Pz.Patr.66 (HL). They used for nominal penetration a virtually infenitely thick plate (for this warhead = 300mm) and measured the depth of penetrtation from the jet a specific number of times. In explorative trials, they then plotted all test depths for each obliquity and compared the mean values graphically. This penetration is called "Testleistung" and usually is much in excess of what was rated penetration (compare attachment).

They then used normal ballistic test plates set at reference obliquity against a series of shots with a witness plate spaced a distance behind and recorded entrance hole, exit hole and the state of the test plate. This allowed an assessment how many times the warhead defeated the armor plate using judgement in relation to the smallest figure obtained at reference obliquity (60°).

F.e. for this rifle grenade the "Testleistung was 208 mm (sic!) at normal impact ( the 1/3 improved liner had 248mm Testleistung). However, only 20% of the warheads also defeated the witness plate behind a 140mm armor plate at 30°, while an improved liner geometry yielded 66%. Rated penetration was often only half as high as Testleistung because it needed to be reliable penetration, not mean.
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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 12 May 2020 21:54

Thanks, great info

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 14 May 2020 21:43

This report from the end of May 1942 has notes on the Pzgr 39, Pzgr 40 and Spgr, for both the KWK 40 and StuK 40 and also the Pak 36 76.2. They mention some interesting notes in regards to effects,and on some short-comings. But they do not mention HL types at all. I would suspect that these weapon systems are in very limited use at this date, and that HL ammunition for them has not been fielded. Given the earlier date seen in the StuG report, I would suspect that Panzer IV with the shorter KWK 37 might have access to it also.

http://www.panzer-elmito.org/panzertrup ... 942_E.html

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Denniss » 15 May 2020 12:11

That report focusses more on the long-gunned new PzJ 38, Pz III/IV and StuG than on ammo types.
It also notes the cartridge ejection issues for long-gunned Pz IV and StuG

Nice: 1800m kill with a 7.62cm gun, 1200m with a long-gunned Pz IV. The long-gunned Pz III was useful up to 400m (I assume against T-34 and similar)

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 15 May 2020 14:41

Denniss wrote:
15 May 2020 12:11
That report focusses more on the long-gunned new PzJ 38, Pz III/IV and StuG than on ammo types.
No, it mentions the ammo types specifically. My point is that HL ammunition for the longer barreled weapons may have had a later introduction date.

It also shows that Pzgr 39 was used by the longer barreled weapons at this time. And that Pzgr 40 was not used much. Mostly because of the satisfactory effects of the Pzgr 39.

Later reports, when HL ammunition was available for these weapons, specified that they should be used so as to save on Pzgr 39. Clearly they were in use some time during 1942.

Image

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Brady » 23 Jun 2020 01:26

So the Earliest use of HEAT by the Germans in there 75's was January of 42 ?

The In service dates for these 7.5 cm KwK 37 rounds being after that obviously ?

Gr.38 Hl - High Explosive Anti-Tank
Gr.38 Hl/A - High Explosive Anti-Tank
Gr.38 Hl/B - High Explosive Anti-Tank
Gr.38 Hl/C - High Explosive Anti-Tank

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 23 Jun 2020 08:42

Brady wrote:
23 Jun 2020 01:26
So the Earliest use of HEAT by the Germans in there 75's was January of 42 ?

The In service dates for these 7.5 cm KwK 37 rounds being after that obviously ?

Gr.38 Hl - High Explosive Anti-Tank
Gr.38 Hl/A - High Explosive Anti-Tank
Gr.38 Hl/B - High Explosive Anti-Tank
Gr.38 Hl/C - High Explosive Anti-Tank
Clearly, the Germans had HL/B sometime before the end of 1942. That is, for L43 and L46 and L48 weapons. Not sure anyone has determined when the L24 weapons would have it. HL/C seems to be very early 1944 or even a month or so before. HL/C seems to have a tracer, not sure if HL/B had one ever.

It is certainly proven that the Germans were ramping up Pzgr 39 in 1942, but the need to have HL/B augment, or even be the dominant main round, might be the case. By the time of Kursk, it seems that Pzgr 39 production might be much better.

The Germans would almost certainly move the L24 weapons into the better HL series. They put the 7,5 cm L24 in Panzer III, had old StuGs using it, old Panzer IV, as well as 251 HT and armored car variants tossing around these rounds.

It really is an important ammunition type that I don't think many historians, wargamers or others recognize.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Brady » 23 Jun 2020 19:12

Well, as a Wargamer/Creator, it's something I am very keen on nailing down, and with your help it is much clear to me now, Thanks for that, btw.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by critical mass » 24 Jun 2020 10:19

I can check my sources. But I remember to have seen Ausf. C in a 1943 dated document.
1944 all development efforts were put into more potent Ausf. C /KLW, which was a different thing, basically HEAT-FS (KLW: Klappleitwerk -with extendable fins just like the large capacity mine shells and R4M rockets) to counteract degrading spin-effects as the shell left the rifled gun barrel.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Mobius » 24 Jun 2020 19:58

critical mass wrote:
24 Jun 2020 10:19
I can check my sources. But I remember to have seen Ausf. C in a 1943 dated document.
1944 all development efforts were put into more potent Ausf. C /KLW, which was a different thing, basically HEAT-FS (KLW: Klappleitwerk -with extendable fins just like the large capacity mine shells and R4M rockets) to counteract degrading spin-effects as the shell left the rifled gun barrel.
Same here. I think I have the HL/C as early as 8/1943 for some guns. But for others not until mid 1944.

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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Yoozername » 24 Jun 2020 20:25

This document from December 1942 shows that both HL/A and HL/B are standardized for the KWK 40 and StuK 40. Interestingly, it list tracers (L'spurhulse) for both?

Also, it shows the propellant for the Pzgr 39 is 2.43 Kg at this time. Later documents show it to be 2.51 Kg.
dez42.jpg
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Re: Report on initial use of HEAT (Garnet 38) 7,5 cm StuK 37 01/23/1942

Post by Mobius » 24 Jun 2020 22:49

Yoozername wrote:
24 Jun 2020 20:25
This document from December 1942 shows that both HL/A and HL/B are standardized for the KWK 40 and StuK 40. Interestingly, it list tracers (L'spurhulse) for both?
Why is that surprising? You posted diagrams of the 4 types of HL and only the early HL did not have a tracer.

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