A Shortage of Guns

Practice shows that processes in the army that flow slowly tend to rapidly accelerate after the first combat engagements. This observation applies to the German SPG program. The Germans began working on these vehicles in the second half of the 1920s, but achieved very little by the start of the Second World War. This was in part due to unrealistic expectations, particularly in the case of tank destroyers. The Germans army dreamed of high speed tank destroyers with a fully rotating turret on a halftrack chassis. Such vehicles were even built, but only as prototypes and small production batches. As a result, the Germans quickly had to build tank destroyers out of whatever was available after the war began.

Vehicles of the 128th Tank Destroyer Battalion. The vehicle in the front is the best known conversion of a Pz.Kpfw.II tank carrying a 50 mm Pak 38 gun.

5 cm KwK Penetration Tables

Anti T-34 Tactics

"Translated from German

Chief Inspector of the Land Forces at the Supreme Command of Land Forces

#126/42

Secret

Supreme Command of Land Forces HQ

May 26th, 1942

Directions for combat of our tanks against the Russian T-34 tank

Characteristics of the T-34 tank:

The T-34 tank is faster, more maneuverable, and has superior off-road mobility than our PzIII and PzIV tanks, and its armour is thicker than the armour of our tanks. Its 76 mm gun surpasses our 50 and 75 mm guns in penetration. Its advantageous positioning (sloped position of all surfaces) helps shells slip off.

T-34 Spaced Armour

"To the Chair of the State Committee of Defense, comrade Stalin

We report on the results of testing German and domestic HEAT and subcaliber shells against a T-34 hull and spaced armour plates and on improving protection against these shells. This work was performed by GABTU, TsNII-48, and factory #112.

As a result of the trials, it was determined that:

1. T-34 armour is insufficient against HEAT and especially subcaliber shells. The most vulnerable parts of the tank are the sides, the turret, the overtrack hull, and to a degree the rear.
   German 50 mm subcaliber shells with a muzzle velocity of 1200 m/s penetrate the side of the tank from 1260 meters, the turret from 690 meters, the overtrack hull from 530 meters, and the rear from 360 meters.
   The front is impenetrable, aside from the connecting joint, which can be penetrated from 600 meters.
   The German 75 mm HEAT shell can only penetrate the lower hull side, destroying the bottom of the overtrack hull and the suspension.
   Additionally, the HEAT shell destroys holders and anything that sticks out when it hits the rear, and can penetrate the roof of the hull if it hits low enough on the turret.
2. As a result of trials, it was determined that the best measure against HEAT and subcaliber shells is spaced armour, located 100-600 mm from the main armour. In order to protect against HEAT shells, an iron plate only 4-5 mm thick is enough. To protect against subcaliber ammunition, 16 mm of armour is necessary.
   As a result, when the sides of the tank have spaced armour 16 mm thick, the T-34 will be almost completely protected from 50 mm subcaliber and 75 mm HEAT shells from a range of 50-360 meters.
   We ask that you let us produce T-34 tanks at factory #112 to test in battle, in two variants:
1. First variant: 15-16 mm screens for the upper and lower sides and turret. The mass of the tank will increase by 2622 kg, which will make the tank 1152 kg heavier than a mass produced factory #183 tank.
2. Second variant: upper and lower sides with spaced armour 10-15-16 mm thick. The mass will increase by 1833 kg,  which will make the tank 363 kg heavier than a mass produced factory #183 tank.

Deputy Chief of GABTU, Major-General of the Tank Forces, Korobkov

People's Commissar of Tank Production of the USSR, Zaltsmann

State Committee of Defense, decree #2594ss

Moscow, Kremlin
December 7th, 1942

The State Committee of Defence decrees that:

In order to improve protection of tanks from HEAT and subcaliber shells, the following must be done:

1. The People's Commissar of Tank Production (comrade Zaltsmann) and factory #112 director (comrade Rubinchik) must produce 46 T-34 tanks with spaced armour by March 1st, 1943, as a part of the quota for the first quarter of 1943. The variants are as follows.

Variant	Amount	Tank part	Spaced armour thickness in mm	Space between armour plates in mm
1	23	Lower side Upper side Turret	15-16 15-16 15-16	630 120-260 70-150
2	23	Lower side Upper side	15-16 15-16	630 120-26

2. GABTU (comrade Fedorenko) must test these tanks in combat during February and March and present GOKO with conclusions.

3. The People's Commissar of Tank Production (comrade Zaltsmann) and factory #38 director (comrade Yakovlev) must develop spaced armour for the T-70 by February 15th, 1943, test two prototypes together with GABTU. Present GOKO with conclusions by March 25th, 1943.

I. Stalin."

RGASPI 644-2-115

However, the T-70 wasn't lucky enough to get extra armour. The entire section is crossed out and marked "exclude completely".

Comparative Testing

"Brief technical report on the development of protection against subcaliber and HEAT shells

1. Resistance of the T-34's hull against HEAT shells
During the course of the war, the German army obtained new types of shells: subcaliber and HEAT. Trials of 75 mm German and 76 mm domestic HEAT shells against a T-34 hull showed the following:

Tank component	At angle	Resistance of component
		75 mm German HEAT	76 mm domestic HEAT
Front plates	0	No penetration	No penetration
Lower side	90	Penetration	Penetration
Lower side	60	No penetration	Penetration
Upper side	90	No penetration	Penetration
Rear	180	No penetration	No penetration
Turret	90	No penetration	Penetration

The table shows that domestic HEAT shells have superior penetration compared to German HEAT shells, as those can only penetrate the lower side of the tank, and at angles close to normal. A special feature of these shells is that due to their HE component, they do not lose penetration at a distance, meaning that the T-34 can be penetrated from a significant range. As for the HE effect, it is somewhat greater than the effect of regular HE shells.

When the shell hits the side of the tank near the overtrack hull or the suspension, they are destroyed. If the lower part of the turret is hit, the roof of the hull is dented or destroyed. When the rear is hit, hatches, exhaust pipe shields, bolts are torn off.

The 75 mm German HEAT shell is not effective against the T-34's armour. These shells are only a serious threat to the sides of the tank at any range.

2. Resistance of the T-34's hull against subcaliber shells

Trials of the T-34 hull showed that its various components in various positions relative to the shooter can be penetrated from the following distances:

Tank part	Shell caliber	Range in meters at the following angle
		90	80	70	60	50	40	30
Lower side	50 mm 37 mm	1260 380	1155 360	980 310	775 200	530 10	250 No penetration	No penetration No penetration
Upper side	50 mm 37 mm	530 15	495 No penetration	420	300	115	No penetration
Turret	50 mm	690	660	565	410	205	No penetration

The table shows that the T-34 is weakly protected from subcaliber shells, as important components can be penetrated from significant distances at relatively sharp angles, which limits the area of maneuver in relation to the enemy. Only the front of the hull is impervious to subcaliber shells and, to a lesser degree, the rear, penetrable at a range of 360 meters.

To compare with regular sharp-tipped German armour piercing shells, the 50 mm shell can penetrate the side from normal at a range of 900-1000 meters, and the 37 mm shell at 150 meters."

RGASPI 644-2-115

German Experience in 1942

I have written many times that penetration achieved on paper is no match for penetration achieved in combat. The Germans seem to have been in agreement, issuing a document describing effective ranges from various weapons against T-34 and KV tanks on June 21st, 1942. A translated version of the captured order containing this data is stored in CAMD RF 208-2511-1049.

Type of gun	Type of shell	Range	Tank	Effect	Notes
50L/60 tank gun	PzGr. 39	600-700	T-34 (turret)	Penetration. Ammunition can explode and the tank can burn.	At long ranges, it is still possible to jam the turret and destroy the gun.
	PzGr. 40	300-400	T-34 (turret)	Penetration only.	Same as above.
	PzGr. 40	600-700	KV-2	Penetration.	The armour is about 80 mm thick. At longer ranges, the gun can be damaged.
50L/42 tank gun	PzGr. 40	Point blank	T-34	None.	It is possible to jam the turret or damage the gun.
75 mm gun (PzIV)	Hollow charge	Up to 700 m.	T-34 (turret)	Penetration.	Crew can be knocked out by the shockwave.
	Hollow charge	Up to 2000 m.	T-34	Suppressive fire.
	Hollow charge	Up to 800 m.	Type II (all parts)	Penetration.	Tank is easily ignited.
75L/43 tank gun	PzGr. 39	Up to 800 m.	T-34	Penetration of the front turret and hull.	Under favourable conditions, the side can be penetrated at 1200 meters.
	PzGr. 39	Point blank	KV-1 (side)	Penetration.
Light field howitzer	PzGr. Rot	600	T-34	Damage to the gun.	23rd TD reports that the shell can be effectively fired from up to 1000 m. at tracks. Fire from reverse slopes.
	PzGr. Rot	400	T-26	Penetration.
	PzGr. Schwarz	300	T-26	The turret is destroyed.
105 mm leFH 18	PzGr. Rot	1200	KV-2	Front armour screen penetrated.
	PzGr. Schwarz	1000	BT	Penetration
	PzGr. Schwarz	1000	T-34	Penetration of the front hull.
50 mm Pak 38	PzGr .40	300	T-34 (turret)	Penetration	23rd TD reports effectiveness. At 800-1200 meters, the angle of meeting the sloped armour is more favourable.
	PzGr. 38	300	T-34	Penetration
	PzGr. 38	300	KV-1 and KV-2	Penetration of side and rear hull.	When shooting the rear at up to 1000 meters, there is a chance to set the tank on fire.

"The casing of PzGr. 40 frequently bursts, and the shell jams.

Rules of using AT guns: Fire from all weapons at proper distances. In cases of massed tank attacks, move the guns into the open. Against the T-34 tank, artillery fire must be concentrated, even if the armour cannot be penetrated with shells."

This document doesn't really tell us anything that we didn't know. The short 50 mm gun is ineffective at fighting T-34s, even with APCR. The longer gun of the same caliber is a little better, but only then against the turret, and not the hull (explaining the short life of up-armoured T-34s). APCR doesn't do as much damage to the insides as APHE. In this case, where the 50 mm APCR can penetrate the T-34's turret, it doesn't cause detonation of the ammunition like APHE does. 

It's interesting to note the obsession with the T-34. Heavier KV tanks are also present (as well as a drizzle of light tanks), but the T-34 receives greatest attention, with more rows dedicated to its destruction, plus additional instructions to fire even if it's ineffective.

The report contains descriptions of tactics I have already posted, along with some new points. For instance, they praise Soviet artillery.

"Enemy artillery has achieved successes in control and concentration of fire. There are cases of massed artillery fire. Because of this, we are forced to loosen our formations.

Reserve positions, ranging guns, and "migrating" guns are used skilfully. Artillery positions are masterfully camouflaged."

It is also noted that the amount and effectiveness of Soviet tank units has increased. In connection with this, tactics must be revised.

"Tanks must be constantly, up to the moment of the breakthrough, be supported by artillery fire (sometimes smoke). If possible, dive bombers must also be used.
...
It is necessary for tank units to occupy favourable positions (preferably reverse slopes), wait for enemy tanks, and then fire on them. These tactics bring greater success than excessive heroism demonstrated by frontline units."

And in the end, one little tidbit that will prove to be the curse of German vehicles for a few years to come: "There are many cases of breakdowns when they need to tow vehicles of equal or greater mass."

50 mm APCR Effectiveness

While exploring the confusion among Soviet battlefield investigators with German HEAT and APCR shells, kris_reid discovered the following curious fragment.

"...62 mm of armour was penetrated. A notable characteristic of this penetration was that both shells exploded in the fighting compartment without harming anyone, aside from the company commander, who was stunned.

During the same day, another Valentine was sent out without proper preparation, and was also hit.

Conclusions:

1. There are still combined forces commanders that do not understand tank tactics.
2. The enemy has a long-barrelled 50 mm anti-tank gun that fires thermite shells that can burn through 62 mm of armour. The shell itself burns up and the remainder is ineffective at harming the crew."

50 mm gun firing HEAT shells? Of course not. The damage described (little internal damage, no trace of shell) is characteristic of APCR. After penetrating the armour, the hard tungsten carbide core shatters into small pieces, which are difficult to recognize as a penetrating element. 

Caliber Breakdown on the Eastern Front

More interesting data from Igumnov's thesis, percentage breakdown of damage to tanks vs the caliber responsible. From left to right: 20 mm, 37 mm, 47 mm and 50 mm L/42, 50 mm L/60, 75 mm, 88 mm, 105 mm, 128 mm, Panzerfausts, and Unknown. 

The rows are as follows: 

Before September 1942

Stalingrad Operation, fall-winter battles of 1942-1943

Central Front, Orel Operation, 1943

1st Belorussian Front, summer operation of 1944 (June-September)

1st Belorussian Front, winter operation of 1945 (January-March)

1st Ukrainian Front (January-May 1945)

4th Ukrainian Front (January-May 1945)

1st Belorussian Front, Oder-Berlin (1945)

2nd Guards Tank Army in the Berlin Operation

German Analysis of the T-34 and KV

The Red Army didn't just perform their own tests, they let the enemy do it for them. This is one such case, where an enemy AT guide is used to suggest improvements to their own tanks.

"To the chief of GABTU's 3rd Department, Military Engineer 1st grade, comrade Afonin
October 10th, 1941

As a result of examination of a document published by the German commanders titled "Memo on fighting Russian tanks", it was established that:

1. Live fire tests of the T-34 and KV from the front and rear, as well as the turret from all sides, reveals that:
1. The T-34 is superior to the KV in this regard. The T-34 resists all artillery from 28 mm to 75 mm inclusive. 
1. The KV can be penetrated under the following conditions:
1. With the 47 mm gun from 50 meters.
2. With the 50 mm gun from 50 meters.
3. With the 50 mm model 1938 gun from 250 meters.
2. The tanks can be penetrated with larger calibers: the 88 mm AA gun and 105 mm gun:
1. KV from a distance of 1000-1500 meters.
2. T-34 from a distance of 100-800 meters.
2. Firing on the sides of the tanks shows inverse results. Namely:
1. The T-34's lower side, behind the suspension, is weak. It can be penetrated by 28 mm guns at 400 meters.
2. The sloped plate of the turret platform is inferior to the KV in resisting two types of shells, specifically:
1. Model 1938 50 mm AT gun, armour piercing grenade:
1. KV can be penetrated at 400 meters.
2. T-34 can be penetrated at 700 meters.
2. 105 mm gun, armour piercing grenade:
1. KV can be penetrated at 300 meters.
2. T-34 can be penetrated at 700 meters.
   In all other cases, the armour of the T-34 and KV is equivalent.
3. Firing on the suspension reveals that the T-34, due to its high density of road wheels and thin track pins is vulnerable to HE shells from the 75 mm gun.

Based on this data, if the German conclusions are correct, then we deem it necessary to direct your attention to improving the T-34 in the following ways:

1. Add armour screens to the turret platform sides, increasing them to 60 mm.
2. Protect the turret ring from the front and side to prevent it from jamming.
3. Add 25 mm skirt armour to increase the thickness of the vertical side armour.
4. Develop smaller road wheels with internal cushioning and a smaller diameter for the same axles.

GABTU NIP chief, Colonel Romanov

GABTU NIP Regimental Commissar, Dolgov

Scientific-Technical NIP Advisor, Military Engineer 1st grade, Gluhov

Chief of the 1st Department of GABTU NIP, Military Engineer 2nd grade, Sych"

CAMD RF 38-11355-158

This report appears to be consistent with the other German AT tactics manuals, as well as the Tigerfibel, which also instructs that the gunner should hold fire at a T-34 until it reaches 800 meters. The 100 meter figure is not a mistake in the Russian translation, the original document did indeed state that the T-34's upper glacis is only penetrable by the 88 mm FlaK gun at 100 meters.

It is interesting that the KV-1 is not mentioned in the areas for improvement. Looks like it was already deemed a developmental dead end by some, even in the fall of 1941, although it continued fighting successfully for years.