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Guide and History to the 7,5 cm KwK 37 L/24

In this guide is about the 7,5 cm KwK and StuK 37 L/24 (as well as modernized K.51). The gun was a prewar development of a compremise of firepower to size. Duo to its size and weight, as well as ammo development put it in a role of multipurpose on a great amount of different vehicles, used prewar till the very end.

(The long name is Kampfwagen Kanone and Sturmkanone, meaning Tank Cannon and Assault Cannon.)

In the following i will go over the:

  • History
  • Vehicle
  • Ammo
  • Guide regarding the ammo
  • Tactics
Panzer IV Ausf.F1 the most famous and last variant of the IV to have the L/24

History:

The Armament:

The 7,5 cm KwK 37 L/24 was an interwar early development of a short tank gun, intended for infantry support, reinforced structure assault as well as to destroy enemy tanks.

It was developed very early in the interwar period as a as small as possible 7,5 cm L/20 gun, based on a WW1 L/20 infantry/mountain gun. This also marked the switch from 7,7 to 7,5 cm guns and was intended to be used in the Großtraktor.

7,5 cm KwK L/20 for the Großtraktor

The L/20 gun was seen as too weak, as such the barrel was increased to L/24. This increased the overall performance across all ammo types by 20 m/s, to 420 m/s for the 5,74 kg HE round which could already penetrate ~30mm RHA.

Primarily intended to fire HE and Smoke rounds, it also received APCBC ammo, with an intended performance to effectively engage every medium target at 30° and 500m range. At the time, with adequate performance, as the tanks usually only ranged in armor thickness of 13-30 mm.

With the failure of the Großtraktor, a new smaller chassis for infantry support was in development, the Pz IV, which was, at the time still just the Begleitpanzer.

The Begleitpanzer was one of 2 types of intended tank concepts by Guderian, along the Zugführerwagen (Pz III). This being the infantry support tank and the anti-tank tank with different intended roles. Despite having different strengths, the concepts were still intended to be cross-compatible, being both equipped with powerful guns with AP and HE ammo. Being a 7,5 cm gun and a 5 cm gun, respectively. However the 5 cm gun was initially not available in time, as such the 3,7 cm KwK L/45, as also used on the Leichttraktor, was used.

While fitting the requirements, the gun was finalised in 1937 and put into main production, as well as adapted as the StuK 37 for the StuG III.

StuG III with removed superstructure, the gun is mounted to the floor.

This gun was a good small package, reaching the required range of 6.200 m and equipped with a wide array of ammo, including HEAT (which was only issued later on in 1940, as it was feared that it could fall in enemy hands.)

Basic ammo sheet of the 7,5 cm KwK/StuK 37 L/24, more info and available ammo types down below.

While a good gun, it wasn't seen as the perfect choice for the future. A new requirement was overall for a tank armed with a 7,5 cm gun at least as powerful as the FK 16 n.A. to combat the most heavy enemy tanks, such as the Char 2C from at least 600m/30° (45mm).

7,5 cm FK 16 n.A. L/36

There were plans to replace the L/24 gun with the aforementioned 7,5 cm FK 16 n.A. L/36. This was a modernized WW1 gun, originally the 7,7 cm FK 16 L/35. In the interwar period the standard caliber was changed from 7,7 cm to 7,5 cm. The whole gun was relatively heavy and only on a limber with wooden spoked wheels. This meant that it was only able to be horse-drawn. Alternatively the gun also existed as the 7,5 cm Flak 16 n.A. L/36 on a pedestal mount, as the Flak 16 n.A. It was mounted on the Krupp Daimler KD-I as a dual AA/AT vehicle, which was highly liked by the Reichswehr for its overall performance.

Krupp Daimler KD-I with 7,5 cm Flak 16 n.A. L/36

However due to its construction of the recoil railing below the gun as well having 2 piece ammo, it could not be mounted in the Pz IV turret without major redesigning. This was seen as not worth it. Testing of mounting was made in a Großtraktor, following development was directed to the 7,5 cm K. L/41. This gun did not enter main production, but was mounted on a couple of prototype Pz.Sfl.II mobile AT-vehicles. It eventually developed into the 7,5 cm KwK 40 L/43, which with the Pz IV Ausf.F2 replaced the aforementioned 7,5 cm KwK 37 L/24 as the main armament of the Pz IV.

Großtraktor with the experimental reworked 7,5 cm Fk 16 n.A. L/36

Upon the start of replacement of the 7,5 cm KwK/StuK 37 L/24 on the Pz IV Ausf.F2 and StuG III Ausf.F, many of the guns filled the stock of warehouses, because of change of roles resulting from the war. However the gun was still an effective armament, being a 7,5 cm gun after all, and with the addition of the Gr.38 Hl/B and /C, the anti armor performance also grew to a respectable performance.

Drawing of the main production KwK 40 L/43. Note the new double baffle muzzle brake.

As mentioned above, many of the guns filled the stock, however guns were needed everywhere. Just disregarding such armament was out of the question. As such the guns were instead modernized (K.51) and mounted on other secondary vehicles, joining the role of infantry support and some AT work.

Such vehicles include, but are not limited to the Sd.Kfz.251/9, Sd.Kfz.233 and Sd.Kfz.234/3. The gun was also placed on fixed mountings.

The name 7,5 cm KwK 37 L/24 however is only partially accurate, as often in official documents it was merely called 7,5 cm KwK L/24. Later in war, an extended barrel to L/34 was developed for the Maus. This was primarily so that the blast didn't go in the air intakes. The velocity increase was only minor, for the APCBC from 385 m/s to ~ 405 m/s, making it still not effective gun when firing APCBC ammo against modern targets.

The Ammo:

The 7,5 cm KwK 37 L/24 (and its brothers) had a wide range of ammo types available along its life. The following sections show more info about each.

Its life started with merely 4 rounds:

  • K.Gr. Rot Pz (APCBC), which later on was supplanted by the Pzgr.39. However, only 2nd grade Pzgr.39 were used on L/24 guns, and this did not noticeably impact AP performance of the gun between the rounds. This was because the Pzgr.39 merely had a higher shatter gap, meaning its performance was better at high velocities and would not shatter on impact at above 700 m/s, unlike the K.Gr. Rot Pz which has a far bigger cavity.
  • Sprgr.34 a further development upon the K.Gr. It was the standard 7,5 cm HE round for all following guns. With a great mix of weight to HE filler with 725g Fp.02 and Np.10 (and later Amatol). It was only slightly modified (simplified production and a 2nd driving band) into the Sprgr.42 for the KwK 42 L/70. 
  • K.Gr. Rot Nb. was the standard issue smoke round, early on still with a copper driving band, later on replaced by the standard soft iron driving band (FES).
  • Kt./Katätsche, which was a standard issue canister shot, either filled with 9 mm hard lead (alloy) or steel balls (later on only found with steel, as lead was getting rare), intended to fight Infantry and low flying aircraft at short range.

The APCBC and HE rounds were also developed with an addition of aluminium powder, for increased incendiary action, these had the addition of "Al." at the end of their name.

Upon extending the service the Gr.38 was issued, after being highly wanted and required by the troops, it was only issued in 1940, as it was feared that the enemy would capture and copy it.

  • Gr.38 Hl. was a dual-purpose steel liner HEAT round. It was issued in 4 versions along its service life, as standard Gr.38 Hl, then /A, /B, /C with ever-increasing penetration. Due to its nature of being HEAT, it had great HE performance on the outside and inside of tanks, combined with great penetration against armor and concrete. Since the 7,5 cm L/24 was a rather low velocity gun, the kinetic AP ammo was almost completely replaced by this chemical energy penetration ammo, which did not lose penetration over distance and was cheaper in production, not requiring high grade steel and hardening techniques.

Overall the ammo includes:

AP:

(Early production still without tracer, but during production implemented.)

HE:

Historic penetration 30mm/10m and 26mm/500m

Utility:

Early with copper dtiving bands and 423 m/s, replaced by FES driving bands.

Adapted 7,7 cm Kt. 7,5 cm Kt. KwK may be slightly different. 280 hard lead (alloy) or steel balls.

Guide:

In-game the gun is represented in all 3 forms on many different platforms, the Pz IV, Pz III, Sd.Kfz.251/9, Sd.Kfz.234/3, with extended barrel on the Maus and E-100.

It is represented with each ammo type it had, with the exception to the canister shot. As such I will stay with the in game available, which is the same as the best available ammo that was developed for the gun.

It's mounted primarily on vehicles below BR 2.0, with the exception of the Pz III Ausf.N at 3.0 and Maus/E-100 at 7.7 (where it is only a coax).

While it is a low velocity gun, it is not without a bite, as at BR 2.0 many enemies can relatively easily be destroyed by the default K.Gr. Rot Pz APCBC round.

Ammunition:

  • The K.Gr. Rot Pz

Is a medium capacity APCBC round, all-round usable due to still good filler (102,4g TnTe). Due to relatively low velocity (385 m/s) it has relatively low penetration (45mm/500m) and a strong ballistic dropoff, requiring some skill to use over distances. However, due to the low armor and mostly light tanks it faces, it's still a perfectly adequate round, if you prefer kinetic penetration ammo. The strong drop can be compensated by the great reload speed of the gun. Until you unlock either of the 2x Gr.38 Hl/B or /C, this will be your main choice of ammo, due to high one hit potential. Depending on usage 25-45 rounds should be taken (if the vehicle has such storage available, StuG III Ausf.A at max 39 rounds HEAT and 5 rounds APCBC).

  • The Sprgr.34

It's a basic HEF tracerless round, which can be an advantage. However, due to being a relatively small HE round, it is not usable against all targets. A tracerless round offers its biggest advantage of hiding your point of attack. Until you unlock either of the 2 HEAT shells, this will be a small addition (5 rounds). If you want to make use of the tracerless round (until the Gr.38 Hl/B is also tracerless in game, as it was historically), you should also bring up to 5 rounds afterward. When the filler is corrected some day (725g), it will be on the top end of power for 7,5 cm HE rounds. Additionally, it's velocity is greater than the APCBC with 420 m/s, and as such it's also easier to hit targets.

  • Gr.38 Hl/B and /C

The HEAT rounds are pretty much identical, except penetration and the /B should NOT have a tracer, same for early production /C also didn't have a tracer unlike in game. Unlike with the APCBC, due to its nature of being HEAT, it will detonate on every obstacle, and any additional material on tanks, making it somewhat unreliable. Therefore combined with the high reload speed, you will burn quite quickly through the ammo, as such you should bring 40-45 rounds, and 5 rounds of backup K.Gr. Rot Pz APCBC rounds. Switch to the APCBC especially against big targets such as T-35 and Char 2C, because the HEAT has relatively small after effect. The great filler amount and high power filler gives the ability to overpressure even some light armored vehicles, not limited open topped vehicles. Combined with the highest velocity of the gun of 450 m/s and great reload speed you can shell even long range enemies as it is not relying on velocity to penetrate. Both /B and /C have excellent penetration, with the /C even being able to easily deal with T-34, KV-1/2 and M4 Tanks. Meaning even in an uptier or bringing it to even higher BRs yourself is no problem for such vehicles, nor are all heavy tanks you can encounter at its own BR.

  • K.Gr. Rot Nb.

The smoke round, is generally not needed but, due to very good reload speed, can be effectively used in offensive and defensive usages. Most Pz IVs and the Pz III Ausf.N have their own smoke mortars, and as such it isn't needed for defence. If you want to, you can hide your advancement with shooting a bunch of smoke rounds in front of you or in front of the enemys. Otherwise, if you dont have any HEAT rounds left, and you face enemies you can't penetrate, you can spam shoot some smoke rounds at them and drive away.

Tactics by Vehicle:

The 7,5 cm KwK 37 L/24 guns is only found on 2 (main) types of platform:

  • Medium tanks: The Pz IV Ausf.C to F1 and Pz III Ausf.N, which from early to later gain more and more armor, however overall handle pretty identically. While the Ausf.C has a greater mobility, at the cost of below average armor, they are very good all-round platforms. The Ausf.F1 can be quite effective in an offensive role, due to its good mobility, average (50mm) armor and great reload speed. Even dealing against multiple tanks is relatively easy. Some of the weaker guns you can face can't penetrate you from close up, while from range and with a 30° angle you can even bounce some of the more powerful small caliber guns such as 3,7 cm M3 to M6 and 4 cm 2 pdr as found on the M2A4 and A13 series light tanks and many more. It should not be over-angled with the Pz IV, as the upper superstructure side armor is angled inwards and only 30mm, meaning you are actively reducing your side protection and creating a weak point. The Pz III Ausf.N sits higher, its general armor isn't as good at its BR, however the hull may be able to block some weaker guns found on the light tanks.
  • Light and mobile chassis: The Sd.Kfz.251/9 and 234/3, are both mobile and quick, however relatively thin armored (though due to angles the 234/3 can over medium range even bounce the high power small caliber cannons such as 40mm 2 pdr and 37mm M3 guns. However both should not be used offensively, rather defensively or flanking, not getting hit and rather using the advantages of the low velocity, shell drop and reload speed, by shooting at targets over a small hill, being perfectly safe.
  • There are 2 other vehicles, being the Nb.Fz. which is neither armored nor mobile, it however has 2x main armaments, and mainly survives due to high crew amount and big size. The other is the Maus (and E-100) where the slightly longer barreled variant is found, it can be effectively used in a multitude of situations: destroying light targets, from SPAA to some medium (and heavy tanks, such as the French, through the side or back), disarming or de-tracking enemies and last but not the least luring enemies out of hiding, by making them think you've shot your main gun shell, all while it only was your secondary (hiwever this does not always work, especially against more skilled and knowledge payers).

Sources:

D.460 Reihe (ammo)

Munition der 7,5 cm KwK L/24

Munition der 7,5 cm KwK 40

D. 435 Anlage 7 Munition der FK 16 n.A.

Panzer Tracts No. 4 Pz IV to Großtraktor

German Explosive Ordanace Projectiles and Projectile Fuzes Chapter 5

Covert German Rearmament 1919-1939 by Barton Whaley

Strategic denial and deception by James Wirtz

Panzermuseum Munster (Pictures)

https://www.tankarchives.ca/2019/11/first-try-at-medium-tank.html

(The 7,5 cm KwK L/20 Blueprint)

https://www.amazon.de/Sturmartillerie-French-Language-Didier-Laugier/dp/2840482851

(StuG III with removed Superstructure)

https://www.deviantart.com/futurewgworker/art/Krupp-Daimler-KD1-truck-with-7-5cm-Flak-673873592

https://www.tankarchives.ca/2023/03/porsche-and-militarism.html

(Long barrled Großtraktor)

https://ca.pinterest.com/pin/75cm-kwk40-tank-cannon-scheme--430445676892775133/

https://www.ww2incolor.com/gallery/german-armored-forces-vehicles/17841/sd-kfz-2519-d-%287.5cm%29

https://tankhistoria.com/nations/german-tanks/the-stug/

(7,5 cm KwK 37 L/24 dismounted left side view)

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiGxr2w0_WKAxXPzwIHHS1iNLgQ6vUJegUI-AEQAA&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DPV4KMsS2Kl4&usg=AOvVaw3WL6Bdu-Se6xFuEL2jMI7D&opi=89978449

(7,5 cm KwK 37 L/24 dismounted right side view)

http://www.maquetland.com/article-2447-allemagne-blindes-sturmgeschutz-iii

(7,5 cm KwK 37 L/24 dismounted breech view)


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