Dispersion data for KwK 42 L/70

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seppw
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Re: Dispersion data for KwK 42 L/70

#46

Post by seppw » 12 Jan 2018, 21:41

critical mass wrote:Firing table data reduced to standart deviation ranges for various late ww2 tank guns attached.
edit: 122mm is for BR-471B (APBC), 100mm is for BR-412B (APBC)
Interesting. I remember reading a ft about one of the German 128mm gun. The deviation was lower than even the KwK36's. I don't remember whether it was the Pak80 or some other version though.

This is what I have so far:
Horizontal:
2w_h.PNG
Vertical:
2w_v.PNG
Do you have more values for the KwK42?

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Mobius
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Re: Dispersion data for KwK 42 L/70

#47

Post by Mobius » 12 Jan 2018, 22:38

You have missed reading a number of threads. That information is on them.
Where are you getting your M3 M62 numbers from?


seppw
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Re: Dispersion data for KwK 42 L/70

#48

Post by seppw » 12 Jan 2018, 22:49

Mobius wrote:You have missed reading a number of threads. That information is on them.
Link pls? I seem to be blind.
Mobius wrote:Where are you getting your M3 M62 numbers from?
I can't find the document on my laptop. Hopefully it's still on my desktop. In that case I will upload it next week.

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Re: Dispersion data for KwK 42 L/70

#49

Post by Mobius » 13 Jan 2018, 00:29


Paul Lakowski
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Re: Dispersion data for KwK 42 L/70

#50

Post by Paul Lakowski » 13 Jan 2018, 00:36

Mobius

Nice charts thanks for that!

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Re: Dispersion data for KwK 42 L/70

#51

Post by seppw » 13 Jan 2018, 11:35

Mobius wrote:Pak 80 128mm - It was awhile back;
https://forum.axishistory.com/viewtopic ... 7&t=220123
I was asking for the dispersion values for the KwK42, not the pak80.
Mobius wrote:Did the M3 data look like this?
https://murdercube.com/files/Combined%2 ... ectile.pdf
Probably. I remember reading this file, but I also had another pdf with only 2 or 3 pages.

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Re: Dispersion data for KwK 42 L/70

#52

Post by Mobius » 13 Jan 2018, 16:09

seppw wrote:
Mobius wrote:Pak 80 128mm - It was awhile back;
https://forum.axishistory.com/viewtopic ... 7&t=220123
I was asking for the dispersion values for the KwK42, not the pak80.
It is on the other Panther gun thread "The Panther's H.Dv.119/325 "Firing Table". Unfortunately there are no post ID numbers so I can't direct you there so I have to quote.
Miles Krogfus wrote:Thomas Jentz in "Germany's Panther Tank . . ." page 126 gives some accuracy figures for the Panther gun. Using German data that I have, here are some of my Pzgr.39 figures to meditate about concerning 50% Breite/Hohe scatter: 100 meters 0/.1, 500 meters .1/.2, 1000 meters .2/.315, 1500 meters .45/.55, 2000 meters .6/.8, 2500 meters .9/.11, 3000 meters 1.1/1.5.
Jentz gives these %, and my B/H figures yield:
500 meters Jentz 100/100% (me 100/100), 1000 meters 100/97 (100/97), 1500 meters 100/72 (98/73), 2000 meters 92/49 (91/50), 2500 meters 73/29 (73/30), 3000 meters 55/18 (56/19). Remember that the people doing the "Tafel der Wahrscheinlichkeitsfaktoren" for German firing tables rounded off figures, and the "Tafel" itself gives only to 2 decimal place partial figures. As I have stated before, German FT's give approximate data for artillery, Pak and panzer crews in order to help guide them in combat.

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Re: Dispersion data for KwK 42 L/70

#53

Post by seppw » 13 Jan 2018, 18:36

Mobius wrote:
seppw wrote:
Mobius wrote:Pak 80 128mm - It was awhile back;
https://forum.axishistory.com/viewtopic ... 7&t=220123
I was asking for the dispersion values for the KwK42, not the pak80.
It is on the other Panther gun thread "The Panther's H.Dv.119/325 "Firing Table". Unfortunately there are no post ID numbers so I can't direct you there so I have to quote.
Miles Krogfus wrote:Thomas Jentz in "Germany's Panther Tank . . ." page 126 gives some accuracy figures for the Panther gun. Using German data that I have, here are some of my Pzgr.39 figures to meditate about concerning 50% Breite/Hohe scatter: 100 meters 0/.1, 500 meters .1/.2, 1000 meters .2/.315, 1500 meters .45/.55, 2000 meters .6/.8, 2500 meters .9/.11, 3000 meters 1.1/1.5.
Jentz gives these %, and my B/H figures yield:
500 meters Jentz 100/100% (me 100/100), 1000 meters 100/97 (100/97), 1500 meters 100/72 (98/73), 2000 meters 92/49 (91/50), 2500 meters 73/29 (73/30), 3000 meters 55/18 (56/19). Remember that the people doing the "Tafel der Wahrscheinlichkeitsfaktoren" for German firing tables rounded off figures, and the "Tafel" itself gives only to 2 decimal place partial figures. As I have stated before, German FT's give approximate data for artillery, Pak and panzer crews in order to help guide them in combat.
Those values are already in my table as you can see in the pictures i posted. I'm looking for deviation values in 100m steps. Although it's possible to interpolate, the full firing table would be better.

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Re: Dispersion data for KwK 42 L/70

#54

Post by Yoozername » 13 Jan 2018, 19:34

Mobius wrote:That seems to be a Ian Hoggism. I have his book "British and American Artillery of WWII" and it has 1/25 for the M5 as well.
But it is 1/40 or 1/32 for M1A2 in Handbook of Ballistic and Engineering Data for Ammunition. Volume 2
http://oai.dtic.mil/oai/oai?verb=getRec ... =ADA955369
It's probably off topic from the thread, but the M10 and 3 in ATGs had a greater powder charge than the M1 series (76mm) of guns. The 76mm cartridges were full and the 3 in cartridges actually had 'dead-space' inside them where more powder could have been packed. IF the 3 inch had a higher velocity (some say 2800 fps), THEN the 1/40 rifling may not have been as detrimental. The 76mm cartridges were modified with a longer flash tube inside in late war production to address the smoke issue. Whether this effected MV, who knows. Again, off topic. But interesting that two weapons firing the same projectile, with similar length/rifled barrels could do so with such a difference in powder weight, and supposedly attain the same velocity?

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Re: Dispersion data for KwK 42 L/70

#55

Post by seppw » 08 Jan 2019, 18:04

It's been almost an entire year since I asked for the dispersion values(in 100m steps). Since then we were joined by a couple of new members with a big disposal of primary sources. May I ask again?
Mobius wrote:
13 Jan 2018, 00:29
Did the M3 data look like this?
https://murdercube.com/files/Combined%2 ... ectile.pdf
Assuming it was from this pdf, what about it?

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Re: Dispersion data for KwK 42 L/70

#56

Post by Peasant » 17 Apr 2021, 18:02

On the topic of the accuracy of the soviet 122mm D-25T gun, I got some new info:

According to author's words, this is from acceptance trials of a mass produced JS-2 tank in April 1944, with the gun equipped with wedge breech and the 10T-17 tank gun sight.

Image

JS-2 from Jan 1944 at 1000m. Early gun still with a screw breech.

Image

JS-2 tank November 1944. Gun with sliding wedge breech and gun sight TSh-17. 1000m.

Image

Another one from January 1945. 1000m

Image

and 2000m.

Image

Source: https://yuripasholok.livejournal.com/12728024.html

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Re: Dispersion data for KwK 42 L/70

#57

Post by Yoozername » 17 Apr 2021, 20:02

Pretty good shooting. It has recoil mechanisms above the gun. I doubt it matters.
is2turr.jpg
is2.jpg

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Re: Dispersion data for KwK 42 L/70

#58

Post by Mobius » 19 Apr 2021, 04:27

To compare the 122mm dispersion to German dispersion double the dispersion values.

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Re: Dispersion data for KwK 42 L/70

#59

Post by Peasant » 29 May 2021, 15:26

The soviets have tested the accuracy of Kwk 43 gun on Tiger II. If we compare the R-50 and R-100 values and the distances from the aim point with those of the D-25T gun posted previously, we see that the german gun is generally more accurate, although the difference is less than one might expect.
Attachments
p0021.jpg

critical mass
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Re: Dispersion data for KwK 42 L/70

#60

Post by critical mass » 29 May 2021, 19:02

Why are there always less than the ten prescribed shots in the 122mm (7-9 actual) samples? this obstructs the comparability...

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