75L24 Performance

[rexford]

Some rather interesting information was presented on the Saumur Tank Museum Intranet,

http://musee-des-blindes.intranet.com

regarding the ability of StuG III and PzKpfw IV to hit and kill T34 with the 75L24. French data indicates that the 75L24 fired a 6.8 kg APCBC round at 480 m/s, which is considerably higher than the 385 m/s normally assumed.

At 480 m/s, 75L24 APCBC would penetrate about 75mm at 0m, based on a DeMarre equation estimate from 75L43 performance. With 75mm penetration at point blank, 75L24 could destroy T34's from the side on most hits, and do a job on the turret front of those Model 1941 T34.

Another interesting thread on that site concerned the stories regarding 75L24 adequacy. Wittmann and others knocked out tanks with 75L24 APCBC, and the gun was effective in France and Russia. Other stories and reports beg for HEAT rounds due to 75L24 ineffectiveness with AP, even pointing out that the Germans flew HEAT rounds to locations where Russian armor would be engaged.

The stories regarding 75L24 performance are similar to 75L43, some reports indicate that gun will save the Eastern Front since it kills T34 at 1200 to 1600 meters on every hit, and reports state that PzKpfw IV must be hidden to avoid long range penetration by T34. And T34 can stand at 1200m and be safe.

When weapon effectiveness reports vary so widely, it appears that more than just penetration performance and ammo/armor consistency may be involved.

[Jeff Duquette]

Interesting. The majority of refs I can lay my hands on indicate K.Gr.rot.Pz as Mv = 385m/s, and Gr.38HL as 452 m/s. These velocities (385 for APC\APCBC and 452 Gr38HL) are consistent with information from:

Jentz: “Stug III”

Jentz: “Tank Combat in North Africa”

Chamberlain’s “Encyclopedia of German Tanks”

Speilberger’s “Sturmgeshutz and Varients”

&

Etterlin’s “German Tanks of WWII”.

Personally I have never found a verifiable incident of a Frenchmen being wrong, but in this case is it possible that a typo was involved?

One side note. Take a look at J. Salt’s compilation of WWII Armour Penetration stats for the 75mmL24 firing K.Gr.rot.Pz. Bovington Tank Museums “Fire and Movement” publication indicates penetration of 30 degree homogeneous armour @500yrds as 46mm. Jentz and Chamberlain both indicate 41mm penetration vs. 30 degree @ 100meters..also homogeneous armour. Several other sources indicate 46mm @ 500yrds and 41mm @ 1000yrds. Back out velocity from Milne-de-Marre for both of these different penetration values and what do you get…

[Username]

My ref shows that 7.5cm panzergranatpatrone rot 38mm @60 @500 meters. Also 7.5cm GranatPatron 38 40mm regardless of the distance.

Was there a german 75mm weapon in between the 75L24 and the 75L43? I vaguely remember reading about one. Perhaps a lengthened L3X?

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by rexford:

Some rather interesting information was presented on the Saumur Tank Museum Intranet,

http://musee-des-blindes.intranet.com

.<HR></BLOCKQUOTE>

When I click on the link I get nothing, is that the right address?

[Jeff Duquette]

Paul:

Try

http://musee-des-blindes.intranets.com/login.asp?link=

there is a key for lurking as a guest.

[Username]

"In order to improve Stug III's performance, in 1942, small number of various Stug III models (from Ausf B to Ausf F) was rearmed with 75mm Stuk L/33 guns, which externally resembled 105mm StuH 42 L/28 howitzers causing confusion. In reality Sturmgeschutz was never armed with this of gun. 75mm Stuk L/33 gun was invented by the British, who misinterpreted German photos of Stug III Ausf F with its longer L/43 gun, which had the muzzle break painted out by censors as new type of gun - L/33."

Thats from Actung Panzer website. Somewhat confusing if you ask me.

[Paul Lakowski]

Great site how do I join this D group?

Is it invite only

[rexford]

Saumur Intranet can be joined by filing an application, see web page application "click on".

[rexford]

The 75mm APCBC round fired by the 75L24 with higher muzzle velocity was not the normally listed K.Gr.rot Pz, it was something else.

One of the interesting things that has come out of the Russian Battlefield site is the great number of rounds fired by Russian tank and field guns. Tanks fired 76.2 at 680 m/s, field cannons at 655 m/s except for some rounds at 662 m/s. Many of these rounds and specifics have not been widely discussed or identified

Now, granted that Russian records have been less available than German, but isn't it possible that a couple of 75mm APCBC rounds escaped attention?

I'll try to get more specifics on the higher velocity 75L24.

[rexford]

Regarding Frenchmen never being wrong, my last name was originally L'Oiseau. My grandfather won the Croix de Guerre in France during WW I.

Does this give me "immunity" from being voted off this board, no matter what I say?

[Jeff Duquette]

Field artillery Mv will vary with charge being fired. A US ARMY example 75mm Howitzer M1 firing M48 HE:

Charge 1 Mv = 700 f/s

Charge 2 Mv = 810 f/s

Charge 3 Mv = 950 f/s

Charge 4 Mv = 1250 f/s

Is it possible that the varying Mv for the Russian Field guns you are referring to are simply a function of the charge being employed?

[Jeff Duquette]

<BLOCKQUOTE>quote:</font><HR>Regarding Frenchmen never being wrong, my last name was originally L'Oiseau. My grandfather won the Croix de Guerre in France during WW I.

Does this give me "immunity" from being voted off this board, no matter what I say?<HR></BLOCKQUOTE>

Dam Frenchies are all over the place

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Jeff Duquette:

Dam Frenchies are all over the place <HR></BLOCKQUOTE>

Wheres Major Richard Sharpe when you really need him?

[rexford]

T34 fired 76.2mm APBC at 680 m/s and the field guns fired at 655 or 662 m/s.

The Russian Battlefield states that the carriage for the 76.2mm field guns was not designed for the recoil forces associated with the ammunition(Valera Potapov corrected me when I referred to 76.2mm "crash boom" as an anti-tank gun, it was a regimental or divisional cannon).

So, it appears that 76.2 towed guns have muzzle brakes and reduced velocities to minimize recoil forces on carriage. This is why 76.2mm in T34 has no muzzle brake and shoots at 680 m/s, towed guns have muzzle brake and shoot at 655 or 662 m/s.

The towed guns fire tungsten core ammo at a slightly lower velocity than T34.

For years I wondered if the 680 m/s figure was a typo, and swore by 655 m/s for T34 and those towed cannons. Potapov's site and many discussions on his Military Forum finally resolved this.

It is interesting that T34/85 doesn't have a muzzle brake and Tiger 88L56 does. And SU-100 doesn't have a muzzle brake, but Tiger II does.

Only German vehicles I can think of without muzzle brakes are PzKpfw III, PzKpfw IV with 75L24 and Hetzer. And Jagd Tiger. Didn't PzJg IV with 75L48 and 75L70 go without a muzzle brake?

Sherman 75 and 76 didn't have muzzle brakes, if one looks at 56° glacis versions. M10 doesn't. Stuart doesn't.

Guess it depends on alot of factors whether a muzzle brake is used.

[rexford]

There's a thread on the Saumur Intranet that discusses why the 75L46 had a higher muzzle velocity than the 75L48, and why 75L43 and 75L48 muzzle velocities are so similar.

This thread went into the Russian 76.2mm situation, as well as some other stuff (like the effect of ammo storage room on muzzle velocity, as well as "elbow room" in the turret).

[Claus B]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Username:

Was there a german 75mm weapon in between the 75L24 and the 75L43? I vaguely remember reading about one. Perhaps a lengthened L3X?<HR></BLOCKQUOTE>

There were several.

Spielberger/Jentz: "Begleitwagen..." (p. 174-176) refers to a March 12th 1941 report on discussions at Krupp about an L/33 gun, a taper-bore 7,5cm-5,5cm L/45 weapon and a "7,5cm lg.s.PaK L/40", the latter for the Sturmgeschütz (same weapon is discussed by Speilberger in his book on the StuG).

A WaPrüf report of December 1941 discusses firing tests of a L/34,5 weapon and another report dated 30. December 1942 discusses tests with muzzle brakes on the same gun. The latter report mentions that a 6,8kg "K Gr rot Pz" is fired and reports the effect of different types of muzzle brakes with "Geschoss Vo = 680". An April 1942 report discusses a "7,5cm kwK L/38 (34,5).."

A discarding sabot round ("Treibspiegelgeschosse") is also discussed for the L/33 weapon.

Plenty of fun here, but all these weapons were replaced in production with the L/43 weapon.

There is one weapon which makes me curious, namely the one on the "7,5cm Sfl L/40,8 auf Fahrgestell Zugkraftwagen 5t" - an armoured 5-ton halftrack with a L/40,8 gun developed in 1934 and shipped to North Africa where they were lost. Did they actually go to combat with their 7,5cm L/40,8 guns or were they re-armed?

Claus B