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

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

Post by Yoozername » 08 May 2020 20:12

Korps command post, 01/23/1942

Generalkommando XXVIII AK
Abt. Ia Nr. 147/42 geh.


Copy of a report on the experiences of the Sturmgeschütz-Batterie 667

During the defensive fighting in Pogotsje on 18., 19. and 20.1 the Battery with 2 assault guns has destroyed with the new grenade 4 tanks of 52 tons, 5 tanks of 32 tons and 1 tank medium.


The following experiences have been carried out:

Due to the fact that the 7.5 cm Garnet 38 does not develop a trace of light when firing it and for reasons of economy, the Battery has fired at the tanks to adjust the shot in the first place with punch grenades and only used the Garnet 38 after have made the first impact.
The grenade when hitting the armor, even when it is tilted, practically never bounces. It "sticks". The grenade pierces everything. First it looks like autogenous welding, then smoke, and then the battle tank catches fire.
The orifice produced and the exact effects on the target have not yet been ascertained since the burning tanks are still in enemy territory. In one of the 52-ton tanks it could be seen that the frontal armor had been torn off.
It has been shot at distances between 600 and 1000 meters and the same good results have always been achieved.

The detonator is very sensitive. Small branches of bushes cause the detonation. All grenades that have hit the armor have detonated (important for secrecy).

The ballistic characteristics of the Garnet 38 are similar to those of the Gran.Patr. m.kl.AZ 23 but has a greater range than the drill grenade. After having adjusted the shot with a drilling grenade at distances of between 600 and 1000 meters, it was for this reason necessary to pass the Garnet 38 to discount approximately 100 meters.

On behalf of the Generalkommando
The chief of staff
Last edited by Yoozername on 08 May 2020 20:15, edited 1 time in total.

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

Post by Yoozername » 08 May 2020 20:15

It would seem that they ranged in with normal AP, and once a hit was made, they 'discounted' (subtracted?) 100 meters on the gun sight.

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

Post by Denniss » 09 May 2020 09:02

airming more foward of the enemy tank (or lower the aiming point) so it won't pass over the target due to longer range than the aiming shot

Original doc: http://www.panzer-elmito.org/ca%C3%B1on ... 142_D.html

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

Post by Mobius » 09 May 2020 14:13

That's remarkable. For a few reasons. The only 75mm HL with no tracer was the early one and that didn't have that good of penetration. It shows need for tracers for accuracy. And finally that a gunner could pass off an acquisition from one shell type to another. Good to know if one is making a game simulation.

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

Post by Yoozername » 09 May 2020 19:38

Mobius wrote:
09 May 2020 14:13
That's remarkable. For a few reasons. The only 75mm HL with no tracer was the early one and that didn't have that good of penetration. It shows need for tracers for accuracy. And finally that a gunner could pass off an acquisition from one shell type to another. Good to know if one is making a game simulation.
I agree. Given the date, and apparently the first use of the ammunition type by that unit, it seems they had positive results. But, again, they did not have a chance to closely inspect the targets. Also, given the date, these Soviet tanks may have had the extra armor applied, and that is what is being reported as getting knocked off.

In any case, I also found the use of tracered AP, (K Gr rot Pz/APCBC-HE/6.80 kg/385 m/s), as a range finding method note-worthy. It had both a different velocity (slower) and a heavier weight, so it would need some adjustment to translate the hit for a HL round. I have read of tankers using MG tracer to get a range value. That is, they walk in tracer and note the range on the MG optic, and then can use the AP setting for it. Perhaps good out to 600-800 meters.

I would think that it is actually a HL/A version given the date and results. The earliest version was said to have a penetration of only 45mm. I find it hard to believe KVs are being destroyed by this. The HL/A has a 70mm penetration or so.

I have seen drawings of HL/C with tracer.
g38.jpg
hlc.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 » 09 May 2020 19:53

Unfortunately I don't have the German firing table for the 75mm APC round used.

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

Post by Yoozername » 09 May 2020 20:18

Denniss wrote:
09 May 2020 09:02
airming more foward of the enemy tank (or lower the aiming point) so it won't pass over the target due to longer range than the aiming shot

Original doc: http://www.panzer-elmito.org/ca%C3%B1on ... 142_D.html
yes, that is the website. Also, it is the English translation from that website. Are you translating it also?

The StuK used a range drum. I would suspect that since this was a new ammunition type, the sight/drum was not designed for it. So, it is a work-around. Once they get a hit with AP, they just dial down the range on the range drum (100 meters). It saves on the more useful HL rounds.

viewtopic.php?t=236861

This is a German translation from the English back to German....


Die ballistischen Eigenschaften des Granats 38 ähneln denen des Gran.Patr. m.kl.AZ 23 hat aber eine größere Reichweite als die Bohrgranate. Nachdem der Schuss mit einer Bohrgranate in Entfernungen zwischen 600 und 1000 Metern eingestellt worden war, war es aus diesem Grund notwendig, den Granat 38 zu passieren, um ungefähr 100 Meter zu sparen.

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

Post by Mobius » 09 May 2020 21:46

The early 75mm Italian effetto-pronto HEAT didn't have much penetration either. But, it sort of acted like a HESH round because the blast focus was wide. Maybe this is the case with the HL German shell, it 'sticks'.

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

Post by Yoozername » 10 May 2020 00:38

Mobius wrote:
09 May 2020 21:46
The early 75mm Italian effetto-pronto HEAT didn't have much penetration either. But, it sort of acted like a HESH round because the blast focus was wide. Maybe this is the case with the HL German shell, it 'sticks'.
I thought that reference was to the very sensitive nose fuse going off at all angles. They mention secrecy, I guess if it always goes off, that would keep a secret.

The Italians also adopted the 'spit-back' fuse. Base detonated HEAT rounds were trouble-some. Bazooka rounds would distort or fold up sometimes before the impact could be transmitted through the body and detonate the fuse. This was described as a low order explosion. Even the Panzerfaust could have problems with hitting light metal objects/ I recall a Churchill tank that was hit in the rear, it was not penetrated but the blast and external damage was pretty good. It struck a bin or other non-hardened surface.

Image

https://comandosupremo.com/forums/index ... eciale.52/
The firing exercise against Kw-1 and T34 tanks with the cast steel type turret and the rolled steel turret that took place at the [firing] range of Deba in Poland in October 1942. On the Italian side, the shells were the 75mm EP and 100mm EP with Gnutti fuzes (for the 100mm 2 types, one with a short nose in Zama alloy and one with long nose in duralumin).

Our 75mm EP projectile proved that it could not produce effects against the T34 tanks, while the corresponding grenade (German n.d.r.) HL definitely exceeded it. In fact, while the 75 EP (which despite impressive destruction effects on plates with a thickness of 30mm) had limited efficiency against the plates of the T34 tank with a thickness of 40mm and 45mm, the HL of the same calibers penetrated, at 42º plates of 40mm of laminated steel, and at 49º that of 60mm of cast steel plates. (p. 90)
Our 100mm EP projectiles, on the other hand, have shown that they can produce, on the same T34 tanks, very serious destruction effects, at least comparable to those obtained from the German 105 which also contains about 500 gr. more explosive, and in any case with secondary effects certainly more conspicuous, even when there wasn’t interior detachment. Also on the turret of the Kw-1 wagon (75mm thickness of rolled steel), with an impact angle of 75°, serious injuries were obtained with large interior detachment, and - in one case - also a through penetration of 10x2 mm. These results have surprised the German technicians, some of which have not ruled out that any effects of the putting the tanks out of action, the primary and secondary effects obtainable with our grenade EP may be more useful, than the simple melting perforation achievable with the HL grenade. (P. 96)

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

Post by Contender » 10 May 2020 07:23

Not 100% related but at least for tanks the later telescopic sights had a scale for HEAT rounds:
Image
Yoozername wrote:The StuK used a range drum. I would suspect that since this was a new ammunition type, the sight/drum was not designed for it.
I am unsure if the Sturmgeschütz or Sturmhaubitze for that matter ever had range scale for HEAT, presumably by the time of the 7.5cm Stuk 40 HEAT usage would have become widespread yet the only range scales I have come across for the Sturmgeschütz with the Stuk 40 are for: Pzgr 40, Spr (HE), Pzgr 39 & a micrometer for elevation:

Image
Yoozername wrote:It would seem that they ranged in with normal AP, and once a hit was made, they 'discounted' (subtracted?) 100 meters on the gun sight.
Considering that the 7.5cm Stuk 37 L/24's K.Gr.rot Pz. round had a muzzle velocity of ~385 m/s & the HEAT round's muzzle velocity was ~450 m/s the account's claim seems reasonable.

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

Post by Yoozername » 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

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

Post by Yoozername » 11 May 2020 05:19

I am unsure if the Sturmgeschütz or Sturmhaubitze for that matter ever had range scale for HEAT, presumably by the time of the 7.5cm Stuk 40 HEAT usage would have become widespread yet the only range scales I have come across for the Sturmgeschütz with the Stuk 40 are for: Pzgr 40, Spr (HE), Pzgr 39 & a micrometer for elevation:
Yeah, never said they did. What is your point?

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

Post by Yoozername » 11 May 2020 05:22

Yoozername wrote:
11 May 2020 05:19
I am unsure if the Sturmgeschütz or Sturmhaubitze for that matter ever had range scale for HEAT, presumably by the time of the 7.5cm Stuk 40 HEAT usage would have become widespread yet the only range scales I have come across for the Sturmgeschütz with the Stuk 40 are for: Pzgr 40, Spr (HE), Pzgr 39 & a micrometer for elevation:
Yeah, never said they did. What is your point?
Considering that the 7.5cm Stuk 37 L/24's K.Gr.rot Pz. round had a muzzle velocity of ~385 m/s & the HEAT round's muzzle velocity was ~450 m/s the account's claim seems reasonable.
they had different weights....you didn't factor that? Ok, thanks.

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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 » 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.

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

Post by Yoozername » 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.

As far as the ballistics, the report does say...
The ballistic characteristics of the Garnet 38 are similar to those of the Gran.Patr. m.kl.AZ 23 but has a greater range than the drill grenade. After having adjusted the shot with a drilling grenade at distances of between 600 and 1000 meters, it was for this reason necessary to pass the Garnet 38 to discount approximately 100 meters.
...which seems to be referring to the HL is comparable to the Spgr (HE). But that is saying the velocity is the same but the weights are not. The use of Pzgr rounds as a ranging rounds might be that they are more reliably indicating range possibly from being zeroed.

In any case, it is a good report and somewhat conflicts with other HL reports. Mainly the range use of 600-1000 meters. Many reports (Panzer) claim 600 meters as being the maximum range to use.

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