Video: Big HE Shells vs German Tank Armour

The SU-152 made a name for itself as a tank killer thanks to its big 152 mm gun firing a 40 kg high explosive shell, but how good was this weapon at destroying tanks? Was better ammunition not available? In this video, I go over how 122 mm and 152 mm high explosive shells fared against thick armour compared to purpose made ammunition.

 

Ammunition Storage

 "#01725
June 9th, 1945

In accordance with your letter #843079s dated May 25th of this year, we present the following ideas regarding rational locations of ammunition in ammunition racks and painting of the racks with the goal of prevention of explosions.

For the SU-76

1. Given 35 round of HE, 15 AP, and 10 APCR, place:
1. 11 rounds of HE on the right side, 17 on the left side, 7 under the gun cradle.
2. 15 rounds of AP in the upper bustle.
3. 10 rounds of APCR in the lower bustle.

Street Fighter

 "Tuesday, March 20th, 1945

Bulletin of street fighting experience, a daily publication of the Red Army newspaper For the Destruction of the Enemy

Guards Jr. Lieutenant-Technician M. Litvinov
Guards Jr. Lieutenant-Technician N. Deryugin

Self propelled artillery in street fighting

Self propelled artillery plays a considerable role in street fighting. Only an SPG can approach a fortified building with enemy machine gunners and destroy it at point blank range. The enemy has felt the blows from SPGs and hunts them, sending out Panzerfaust troops and shooting them on the approach. Completion of the SPGs' objectives requires considerable experience from the drivers.

In this article, we would like to share the experience of SPG drivers in street fighting.

The Most Numerous Heavy SPG

Soviet heavy SPGs were initially designed to combat fortifications. When the war came, there turned out to be a much larger variety of targets for them. Wartime heavy SPGs were very different from what was initially envisioned. The Red Army needed universal vehicles that could both fight powerful fortifications and enemy heavy tanks. One of these vehicles was the ISU-152, a replacement for the SU-152 on the IS tank chassis. The ISU-152 became the most numerous heavy SPG in history.

SU-152 and ISU-152 Tactics

The SU-152 is an often misunderstood vehicle. Some think that because of its thick front armour and relatively short gun it engaged enemies point-blank, but in reality it was actually a long ranged fighter, engaging enemies from 1500-2000 meters. In my latest video I explore the tactics behind SU-152 regiments and how they evolved over time.

Wider or Longer?

 

"Based on results of artillery trials of an IS-122 SPG in the amount of 438 shots (222 supercharged) the Gorohovets ANIOP makes the following conclusions:

• The 122 mm IS-122 self propelled gun passed proving grounds trials and can be accepted into mass production.
• The IS-122 has the following advantages over the IS-152 self propelled gun-howitzer, such as:
• Rate of fire is twice as high.
• Ammunition capacity is higher (30 rounds instead of 20 like in the IS-152).
• Muzzle velocity and penetration are higher (by 20%).
• The maximum range is longer (by 3 km).
• It is easier for the crew to work, load ammunition, and prepare for battle.
• Fire at moving targets is more effective."

Via Yuri Pasholok.

Extended Magazines

"USSR NKO

Commander of Armoured and Mechanized Forces of the Red ARmy

July 19th, 1944

#511127

Trials were held to establish the possibility of increasing the amount of ammunition carried in SPGs, which increases the ammunition capacity of the ISU-152 and ISU-122 by 7 rounds and the SU-85 by 5 rounds if necessary.

Additional ammunition is to be carried in the following ways:

Video: SPG or Tank Destroyer?

In this week's video, I take a look at a commonly asked question: what's the difference between a self propelled gun and a tank destroyer? Was the SU-152 either or both? Watch and find out!

Late Replacement

There are many cases in tank building where a very good vehicle appears too late to enter mass production. This was most common at the end of WWII, when a number of development programs were cut due to the end of hostilities. The Object 704 or Kirovets-2 was one such unfortunate project. This was a significant step forward compared to the ISU-152, but the end of the war and revised requirements for heavy SPGs left it no chance of entering production.

Lesson Plan

"March 20th, 1945

Syllabus for technical preparation of crews for usage of tanks and SPGs in spring-summer conditions

Objective: to teach the main rules of  moving over to using tanks and SPGs in the spring and summer and learn the specifics of using tanks and SPGs in the spring and summer.

Time allotted: 12 hours, one hour per day

Location: in classrooms and in vehicles

Training conducted by: technical deputy commanders of companies and battalions

King Tiger Penetration Trials

"10th Tarnopol Order of Lenin Independent Guards Tank Destroyer Brigade

September 3rd, 1944

#0302

To: Commander of artillery of the 1st Ukrainian Front, Colonel General of Artillery, Barentsov

CC: Commander of artillery of the 13th Army, Commander of artillery of the 5th Guards Army

I report that on September 1st and 2nd, 1944, I performed penetration trials against the "T-B King Tiger" tank using 57 and 76 mm guns, a 57 mm SPG, an 85 mm gun on a SU-85, and a 152 mm gun-howitzer on an ISU.

Results of penetration trials:

Heavy Tank Destroyers that Remained on Paper

The KV-14 (SU-152) SPG was accepted into service on February 14th, 1943. It was designed primarily to combat enemy fortifications, but its first use in combat pitted it against German tanks. Work on tank destroyers on the SU-152 chassis began in the spring of 1943. Even though none of these projects was implemented in metal, the work eventually led to the ISU-122.

IS Debut

"Military Council of Armoured and Mechanized Forces of the Red Army

April 1st, 1944

#481904ss

To commander of the 2nd Ukrainian Front, Marshal of the Soviet Union, comrade Konev

The regiments of heavy IS tanks and ISU-152 SPGs consist of the first tanks and SPGs of this type. As tanks and SPGs of the first production batch, they have a number of minor technical drawbacks, as there is not yet sufficient experience in their use. I ask you to take measures and offer assistance in the matters of studying these vehicles in battle, discovery of their usage and technical drawbacks, and study of the best way to use them in battle.

ISU-122S Acceptance

"State Committee of Defense Decree #6430ss

August 22nd, 1944

Moscow, Kremlin

On the acceptance of the ISU-122S SPG with the 122 mm D-25S gun into service and into production 

The State Committee of Defense decrees that:

1. The ISU-122S SPG with a 122 mm D-25S gun designed by factory #9 in accordance with the tactical technical characteristics in attachment #1 is accepted into service.

Object 704 Drama

"Report on the development of the 152 mm ML-20SM SPG

1. The Journal of the Artillery Committee #0254 1943 indicates that, as a result of trials and review of blueprints of the 152 mm model 1937/43 SPG, work should be done to improve the following areas:
1. Gun/breech: get rid of the muzzle brake, introduce a sliding quarter or semi automatic breech.
2. Cradle and recoil elements: simplify the recoil brake, transition to constant resistance to recoil and constant recoil length.
3. Turning mechanism: improve the design to reduce drifting of the aim and reduce effort of turning the aiming flywheel.
4. Frame, loading tray, recoil guard: review the design in order to standardize the parts and reduce their number.
2. By January of 1944, OKB-172 performed a modernization of the ML-20S, which consisted of the following:
1. Removal of the muzzle brake.
2. Introduction of a simpler recoil brake with a constant resistance and constant recoil length.
3. Shorter cradle and recoil elements.
3. Factory #172 began to work on producing a prototype of the ML-20SM. OKB-172 was told that it was expected by February 10th, 1944.
   In practice, work on the experimental prototype lasted until September of 1944.
4. After multiple requests made by the GAU to the NKTP to install the ML-20SM into a mass production ISU-152 SPG at the Kirov factory, this order was only given on October 2nd, 1944.
5. The experimental ML-20SM gun was delivered to the Kirov factory in the first half of October of 1944. As it was established later (December 12th, 1944), the gun was incomplete (lacked a turning mechanism, lacked a prepared location to install it, factory #172 did not respect the established connection between the gun and mantlet)
6. The GAU raised the issue of completing the ML-20SM to factory #172. Factory #172 representatives arrived at the Kirov factory to perform the work there in mid-February of 1945.
7. Factory #172 communicated the following to the GAU in early May of 1945:
1. The ML-20SM is being installed at the Kirov factory not in the mass production ISU-152, but in the experimental "Kirovets-2". Because of this, it is necessary to shorten the cradle and recoil elements. An agreement was reached to make changes to mass production samples, and for now the experimental ML-20SM was installed with a special mantlet (to compensate for the longer recoil elements) and presented to proving grounds trials in this manner.
8. The GAU informed comrades Ustinov, Malyshev, and Fedorenko by letter that it will only accept a fully completed ML-20SM for trials, with all changes required to install it in the new SPG. At the same time, the question of how future-proof the Kirovets-2 is was raised (May 16th, 1945).
9. The GBTU and NKTP replied that they were in agreement with the GAU, and urged the NKV to complete modifications of the ML-20SM, after which it would be sent to trials.
   The NKV insisted that the trials are to be carried out at the GAU main proving grounds without changes to the gun, claiming that it is necessary to discover additional requirements for its improvement.
10. The GAU replied that, if the trials are considered factory trials, the GAU has no issue with trials aimed at determining requirements being carried out at the GAU main proving grounds, and will aid the NKV with necessary service and supplies.
11. The NKV presented a program of trials at the start of August, and the GAU main proving grounds were ready for the trials in mid-August.
12. Factory trials of the ML-20SM at the Main proving grounds began on September 24th, 1945, and concluded on November 13th, 1945. The start and end of the trials were delayed due to a lack of NKV representatives. The GAU informed the NKV that they must be sent urgently on two occasions (September 9th and October 15th). 
13. The report on factory trials arrived at the GAU on December 6th, 1945. The main goal of the trials was to:
    Determine the quality of the weapon.
    Determine the robustness of the system as a whole and its individual components.
14. In total, 65 rounds with normal charge and 244 with increased charge were fired. Overall, including the rounds fired before arriving at the proving grounds, the gun made 576 shots, 440 of them with increased charge.
15. The SPG will be sent to the NIBT proving grounds for GBTU trials on December 21st-25th.
16. The People's Commissariat of Armament gave the order to factory #172 to produce a new MK-20SM including the required improvements described as a result of trials at the GAU proving grounds and NIBT proving grounds.

Senior Engineer of the 2nd Department of the Artillery Committee, Engineer-Major Gorbachev

December 19th, 1945"

CAMD RF 81-12038-588 pp.90-92

Beast vs Beast Killer

If you read this blog, you're probably already familiar with tests performed with 152 mm guns against King Tiger tanks. Fans of the King Tiger needn't worry about unfairness, since the ISU-152 was in turn tested against a Pak 43. A new welded hull, rather than cast, was adopted by UZTM, which already had experience with using this type of hull on IS-2 tanks. The results were quite impressive.

Far East Variety

As I've written before, the tank fleet of the Far East Front was rather heterogeneous. Large amounts of T-26 and BT tanks were preserved there, since there was little for them to do in Europe. When the war moved over to the Far East, these tanks were ready to spring into action.

"Report on the materiel of the Armoured and Mechanized Forces of the 1st Red Banner Army as of August 8th, 1945

Unit	Authorized strength						Actual strength
	KV	T-34	BT-7	T-26	ISU-152	SU-76	KV	T-34	BT-7	T-26	ISU-152	SU-76
75th Tank Brigade	-	86	-	-	-	-	-	43	-	46	-	-
77th Tank Brigade	-	86-	-	-	-	-	-	42	42	-	-	-
257th Tank Brigade	-	86-	-	-	-	-	-	40	-	46	-	-
48th Independent Tank Regiment	21	-	-	-	-	-	21	-	-	-	-	-
335th Heavy SPG Regiment	-	-	-	-	21	-	-	-	-	-	21	-
338th Heavy SPG Regiment	-	-	-	-	21	-	-	-	-	-	21	-
339th Heavy SPG Regiment	-	-	-	-	21	-	-	-	-	-	21	-
455th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
456th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
457th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
459th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
460th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
466th SPG Squadron	-	-	-	-	-	13	-	-	-	-	-	13
Total	21	258	-	-	63	78	21	125	42	92	63	78

Conclusions:

1. The army's units are fully equipped with armoured vehicles.
2. Instead of the authorized amounts of T-34 tanks, the tank brigades are half full of obsolete T-26 and BT-7 light tanks.
3. The 48th Independent Tank Regiment's KV tanks require medium repairs and cannot participate in the operation."

Interestingly enough, at least one of these BT-7 tanks was a refurbished tank equipped with applique armour.

Via Valeriy Lisyutin.