WEAPONS FINNISH ARMY ALMOST HAD IN WORLD WAR 2, PART 3

Other Infantry Weapons

 

 

Flame-thrower M/Kuusinen aka flame-thrower M/44:

Liekinheitin M/44

PICTURE: Finnish flame-thrower M/44 (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (95 KB).

Maximum range:

12 - 15 metres

 

 

Flame:

50 - 70 burst of 1 second

 

 

40 - 60 sec of constant flame

 

Weight:

? kg in action

 

 

 

? kg empty

 

 

Working pressure:

15 at

 

 

Liquid capacity:

9,5 litres

 

 

During Continuation War Finnish troops were using two types of portable flame-throwers - Italian M/40 and captured Soviet M/41-R. While portable flame thrower is extremely lethal within its own limited envelope - like most with flame-thrower designs, M/40 and M/41-R had similar basic limitations. They could be only used to short range and due to them being so large, heavy and clumsy soldier operating them was unable to carry or use any secondary weapon larger than a pistol. As a result soldier using the flame-thrower was basically defenceless if running to enemy soldier(s) that were outside effective range of his flame- thrower. Due to this Finnish Army typically had another soldier equipped with submachine gun to protect flame-thrower operator, but even with this the casualties of soldiers using portable flame-throwers were not light.

During the long trench war period of Continuation War Sergeant M. Kuusinen of Infantry Regiment 1 (Jalkaväkirykmentti 1) made invention that he hoped solve this problem. His invention was a new kind of light flame-thrower that and which could be used with submachinegun. Key of the invention was attaching flame tube of flame thrower to submachinegun, effectively making the two weapons a single combination weapon. Fuel tanks for the flame-thrower were still carried on back as in existing designs and fuel was lead with vents and pipes from fuel tanks to tube. But now the soldier using the flame-thrower could also use the submachinegun if needed and no longer had to rely for assistance of other soldiers so much. Since the weapon was designed for attaching to barrel jacket of any normal Suomi M/31 submachinegun, it didn't require any changes to other existing equipment.

PICTURE: Flame tube of Finnish flame-thrower M/44. Notice how the flame tube has been clamped to submachinegun barrel jacket. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (69 KB).

While this invention of Sergeant Kuusinen may seem like a simple one, it had merit and went through chain of command until it ended to correct desk where its highly useful nature was fully appreciated. It was exactly the type of invention that Finnish Army was looking at the time. Obvious improvement to existing military weaponry, but demanding only little resources for testing and development, while also being with-in limited production capabilities of Finnish industry already hard pressed by wartime production needs and poor availability of raw materials.

This prototype flame-thrower was named flame-thrower M/44. The prototype was first demonstrated in General Headquarters of Finnish Armed Forces (Päämaja) in April of 1944. This demonstration proved successful enough to lead into approval of further development and orders for making blueprints. Finally the development work lead into small experimental series, which was manufactured for field-testing. The field-testing was made by troops of Cavalry Brigade, Armour Division and Engineer Battalion 35. For most part the test results were positive. The basic concept worked as intended, attachment of flame-thrower to Suomi M/31 submachinegun was successful and allowed the flame-thrower operator to use both weapons, hence removing the need for submachinegun-man to cover the flame-thrower operator. Flame-thrower M/44 was able to 50 - 70 short flames or up till 40 - 60 seconds of continuous flame, which was highly impressive performance compared to earlier flame-throwers. Downside was that the flame-thrower M/44 proved to be effective only to range of 12 - 15 meters, with short one second long bursts of flame in often being only 8 - 10 meters long. This was considerably less with the other two flame-thrower designs already in used of Finnish Army. When it comes to range and maximum effective time of use, the test results showed considerable variation - probable reason for this is that many of the nitrogen bottles used for providing pressure were leaking. Hence, again the main reason for the large variation in performance seems to have been quality of raw materials used for manufacturing the prototypes.

In general field-testing feedback suggested that the weapon proved suited in storming trenches, but due to short flame was poorly suited for other sort of combat situations (*). Some soldiers found it light while others still considered it too heavy considering the reduced range, while they agreed that it was handy and easy to use. Standard issue backpack frame adopted for it made carrying this flame-thrower more easier and comfortable than earlier earlier flame-thrower designs. But this new design had also other issues, which required to be ironed out before planned mass-production. These included replacing existing vent types which version that was easier to operate, eliminating of protrusions and sharp corners (for which the flame-thrower operator might get entangled or hurt himself) and lesser material issue. This material issue being that front end of the leather submachinegun sling used to carry the weapon tended to become unintended casualty of the flame-thrower flame and needed to be replaced with fire-proof material. If the nitrogen tanks were filled to full capacity the flame-thrower would also run out of fuel slightly before running out of nitrogen, which was considered a useful feature.

(*) It's worth noting that Finnish Army did very little urban warfare in World War 2, hence this possibility was not even considered.

From these three units only Engineer Battalion 35 battle-tested the M/44 flame-throwers sent to it. The battalion used three of the prototypes to equip strike team of one NCO and six men, which attacked Soviet trenches under the cover of darkness in Kagrakangas 16th of August 1944. Combat-experience from this small battle was less than positive. System used for igniting the flame proved unreliable and small pilot flame in tip of the flame-thrower was considered the likely reason why the Soviets spotted the Finnish strike team too early in this particular battle. Due to being spotted the strike team suffered three wounded. Also Armour Division had reported problems with igniting the flame especially in windy conditions, so apparently there was real room for improvements in that part of the design.

Finnish Army didn't stop the process for introducing flame-thrower M/44 to wait the results of test process. Manufacturing of parts needed for producing 100 of these weapons had been ordered and was to be completed by 15th of July 1944. They were to be assembled in Weapons Depot 1 (Asevarikko 1). Each flame-thrower was to be delivered with five nitrogen tanks and three igniting sticks. The development project seems to have continued at least until 24th October of 1944 at which time there were plans for trying to improve range of the flame a little. However as the report written at that time this would have required increasing working pressure, which would reduce duration between required fuel refill.

PICTURE: Drawing showing structural details of flame thrower M/44. Notice the the two fuel tanks and the nitrogen bottle in between them. The red stamp SALAINEN indicates that the document used to be classified. CLICK THUMBNAIL TO SEE LARGER PIC (76 KB).

Improvements based to testing were also designed and ordered to be implemented for two of the existing test-series flame-throwers and were apparently completed. These improvements may have included earlier designed so-called "dead man's switch" which would extinguish the flame in case of flame-thrower operator becoming wounded or killed. Not more then few dozen of these flame-throwers were made, and most of them were scrapped soon after the war. Only few survived for museum. When Finnish Armed Forces after Continuation War decided to reward those of its soldiers who had introduced it useful inventions, Sergeant Kuusinen was among them and was rewarded with sum of 10,000 Finnish marks for this invention.

After World War 2 flame-throwers played very small role in Finnish weaponry. Wartime M/40 and M/41R flame-throwers were old-fashioned and had seen a lot of use, so they probably were not in best of shape anymore and didn't see much post-war use. What is known suggests that the small number of existing M/44 flame-throwers saw limited post-war training use, but on the long run Finnish military lost interest to flame-throwers and never acquired any more modern flame-throwers.

 

47-mm low trajectory mortar M/Kahva

(47 mm laakaheitin M/Kahva)

PICTURE: Prototype of low trajectory mortar M/Kahva. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (68 KB).

Low trajectory mortar designed by Major Kahva for Finnish Army in year 1942 was designed for shooting vision slots of enemy bunkers and machinegun nests with 47-mm mortar shells. This shoulder fired weapon equipped with a folding adjustable bipod and used normal Mosin-Nagant rifle receiver and bolt for firing 47-mm mortar shells originally introduced for 47-mm Tampella mortar prototypes in 1930's. Hence availability of the ammunition was not too great and while the weapon was equipped with bipod it was quite heavy and must have had considerable recoil. This weapon has simple iron sights on left side of the weapon with the rear sight loaned from M/28-30 or M/39 rifle. Sako Oy manufactured three prototypes, which were field tested, but the weapon was never approved and did not see later production.

Even if the design had not suffered the handicaps mentioned above, it had very little chance of success. Looking at the design it is fairly obvious that it was intended to fill the notch that was soon covered by recoilless rifles. Hence unfortunately the design would have become obsolete almost immediately anyway.

 

81-mm low-trajectory mortar m/Tampella

(81 mm kaasujarrukranaatinheitin)

Presumably intended to fire normal 81-mm mortar shells this low-trajectory equipped with recoil mechanism was developed by engineer H.O. Donner for Tampella, where he worked. Tampella manufactured prototype was tested by Finnish Army in Niinisalo test firing range, but the prototype proved less than successful. What is known the main problem was apparently with unacceptably poor shooting accuracy mainly caused by low muzzle velocity.

 

120-mm low-trajectory mortar m/Tampella

(120 mm kaasujarrukranaatinheitin)

Also this low-trajectory mortar was based developed by engineer H.O. Donner for Tampella during Continuation War. Tampella build at least one prototype which was tested in Niinisalo test firing range multiple times. Basically it was a 120-mm mortar barrel installed on gun carriage of captured Soviet 45-mm antitank-gun with its recoil system. The weapon was intended as possible direct fire weapon against bunkers and possibly as antitank-weapon, but proved unsuccessful. The main problems revealed by testing included gun carriage proving structurally too weak for weapon of this type and poor accuracy presumably due to low muzzle velocity. Test firing report from year 1944 also suggests that there were issues in developing properly working projectile and propellant combination.

 

170-mm base weapon (mortar)

(170 mm tukikohta-ase)

PICTURE: Archive photo showing side profile of 170-mm base weapon. CLICK THUMBNAIL TO SEE LARGER PIC (51 KB).

This was one of the official wartime development projects of Weapons Headquarters for General Headquarters of Finnish Armed Forces (Päämajan Ase-esikunta). It was invention of Major Erkki Paloheimo with at least one prototype built by Oy Wårdström Ab, which also manufactured its ammunition for tests. This Basically the weapon was a 170-mm short-barrel mortar, which fired cluster bomb like antipersonnel projectiles designed especially for this weapon. It had been designed a cheap, easy to manufacture and transport weapon with plenty of firepower against attacking enemy infantry. Since the weapon was planned for frontline infantry and intended for defending own bases, it didn't need to have very long range and range of just 500 meters was considered sufficient. Structurally the prototype weapon itself was a short-barreled 170-mm caliber mortar with base plate loaned from 81-mm mortar and bipod typical to Brandt-Stokes type 81-mm mortars.

While the mortar was structurally very much a typical mortar, the projectile was anything but. While non-standard caliber of the weapon had been chosen due to projectile - 170-mm was considered smallest practical caliber for which this sort of complex cluster bomb like projectile could be developed. Once the projectile hit the ground small gunpowder charge would bounce it back to air and secondary gunpowder charges within it were designed to propel five sub-ammunition projectiles to different directions in 360-degree pattern. These five sub-ammunition projectiles would then explode in pre-set distance (of 5 - 30 meters) from where the main projectile had landed. Since these smaller projectiles were pommiansa (German S-mine) inspired and designed to detonate mid-air the metal fragments from single 170-mm projectile would cover a very large area - some estimates suggest lethal fragmentation covering as large as a hectare. Main parts of the projectile had been intentionally designed to be cheap to manufacture - besides tail with fin assembly and the component in which the fuse was screwed into they were cast iron. Two versions of 170-mm projectiles were manufactured with light version weighting 13-kg and heavy version weighting 17-kg. In addition these also third yet easier and cheaper to manufacture version was under development in February of 1944.

PICTURE: Archive photo showing frontal view of 170-mm base weapon. CLICK THUMBNAIL TO SEE LARGER PIC (50 KB).

Early on maximum range of 500 meters was considered sufficient for the purposes in which the weapon was intended. Test firing suggested that maximum range of 700 - 800 could be achieved with ammunition development and even range of 1,000 meters would not have been impossible, but would have required stronger and therefore heavier barrel for the weapon. The distance to which the secondary gunpowder charges would propel the five sub-projectiles was to decided only after explosive used in these sub-projectiles had been chosen, since the choice of explosive effected lethal area covered by metal fragments and therefore effected efficiency of the projectiles.

The prototype was tested in Santahamina military base (in Helsinki) and town of Mikkeli (location of Finnish Armed Forces GHQ), where live fire testing was done 25th of February 1944. The test firing was successful enough that at that time acquiring of 100 weapons and 20,000 rounds of ammunition was under consideration. Development work and further testing continued several months, since getting the rather complicated fuse system of the 170-mm shell to reliably work as intended proved highly problematic. Ultimately in August of 1944 the project was abandoned. Test firing of 170-mm base-weapon prototype vs. existing 81-mm and 120-mm mortars had revealed that limited manufacturing resources would be wasted if used for introducing of this new weapon. Existing 81-mm and 120-mm mortar ammunition was much more reliable than what the new weapon offered and particularly existing 81-mm mortar equipped with heavy mortar shells was more than capable fulfilling the role in which the new 170-mm base weapon had been intended.

After this project had proved unsuccessful Major Paloheimo focused his intention in developing recoilless rifles. Later Finnish Army rewarded Major Paloheimo with reward of 3,000 Finnish Marks for his development work with 170-mm base weapon. During assessment concerning this reward Paloheimo's superior noted that this weapon concept had been nothing less than spectacular but due to not his fault the limited resources had not allowed developing invention as a mass-produced weapon in available amount of time.

 

Recoilless rifles designed by Major Paloheimo

Another project by Major Erkki Paloheimo for Weapons HQ of Ordnance Department (of Finnish Armed Forces General Headquarters) was developing recoilless rifles in year 1944. The intention of this project was to develop recoilless rifle, which would be suited as infantry support weapon and capable of firing various types of projectiles. At that time the terminology concerning this type of weapon was not yet established in Finnish language, so most original documents refer to these recoilless rifles as reaktioase ("reaction weapon"). Presumably inspiration for this kind of weapon came from German panzerfaust and possibly from two Soviet Kurchevsky 76-mm DRP (Dinamo Reaktivnaya Pushka) recoilless rifles captured already during Winter War.

PICTURE: Kurchevsky's DRP recoilless gun captured by Finnish Army during Winter War. This weapon which the Soviets had installed on a truck may have served as one of the starting points for Finnish recoilless rifle developments. (Photo taken in Sotamuseo). CLICK THUMBNAIL TO SEE LARGER PIC (62 KB).

The first prototype designed by Paloheimo was 47-mm caliber and early on referred as suppiloase ("funnel weapon"). This early prototype was tested in two test-firing events held in March of 1944. It had been designed primarily to shoot German 46-mm rifle grenades to notably longer distances than what normal rifle grenade equipment allowed, but testing proved it capable of shooting also projectiles notably larger than its caliber assuming they were first modified suitable for this purpose. Due to this work was started for developing modifications to panssaripanos m/42 (German HL-handgrenate or hafthohlladung 3), to allow it to be fired from 47-mm recoilless rifle prototype. These modifications included developing new tail and front sections which were added to panssaripanos m/42 and replacing original time fuse with impact activated concussion fuse designed to detonate the warhead when the projectile hit the target. At that time developing even larger projectiles was suggested along plan of developing "bouncing" high explosive projectile to make ammunition more lethal. While the prototype was considered a success, it was still not much more than a starting point for the development work. Variety of structural designs, barrel lengths and funnel shapes needed to be tested along testing of electrical and mechanical firing systems. Also variety of propellants was tested with type of black powder developed for ignition charges (virikeruuti) proving as best suited propellant for this purpose.

Later prototypes were all 50-mm caliber and included:

(*) Documents suggest that while this prototype was originally ordered from VKT, the order may have been later transferred to Oy Wårdström, since later documents mention Wårdström-made prototype with almost similar weight (14.6-kg).

With a benefit of hindsight one can now note that at that time Finnish military made a serious mistake in developing this weapon – instead of deciding what kind of ammunition was needed and developing it, they went and attempted to adapt and modify variety of existing ammunition for this purpose. As the later events show, this turned out be serious mistake. July of 1944 above mentioned 50-mm prototypes were used for testing these projectiles:

Projectile:

Modified:

50-mm mortar shell

Unmodified

50-mm flare for mortar

Unmodified

46-mm anti-tank rifle grenade (*)

Structure reinforced, sealing ring and tail added.

Panssaripanos m/42 (**)

Installed to wooden frame developed for it.

Panssarinyrkki F1 projectile (***)

Equipped with wooden tail section reinforced with iron rings.

Smoke grenade

New tail section and weight added to pulling string.

Blinding bottle M/44

Installed to wooden frame developed for it.

(*) German 46-mm anti-tank rifle grenade. Finnish military had bought these and rifle grenade equipment already earlier.

(**) German HL-handgrenate or hafthohlladung 3. These were antitank-charges with HEAT-warheads.

(***) 100-mm German Panzerfaust klein HEAT-projectile.

Test results from tests done in June 1944 with these projectiles were considered promising and the goal was set in developing a recoilless rifle with longer range than panzerfaust and panzerschreck bought from Germany. Test results from these tests:

Projectile:

test results:

50-mm mortar shell

Good, muzzle velocities 107 - 115 m/sec.

50-mm flare for mortar

Good, burned completely before landing.

46-mm anti-tank rifle grenade

Excellent range, poor accuracy, requires development.

Panssaripanos m/42

Good, worked as intended, armor penetration untested.

Panssarinyrkki F1 projectile

Some issues but worked, 90 m range.

Smoke grenade

Good. 200 m range with 25 degree elevation. (*)

Blinding bottle M/44

Worked as intended, range 85 m.

June 1944 tests revealed that the weapon required following improvements:

Test results were so positive that already 9th of July 1944 General Major Palojärvi (Chairman of Weapons Negotiation Board) suggested for ordering field test series of 100 recoilless rifles from Oy Wårdström immediately once the weapon would have been developed ready for mass-production. However the estimates were not to remain that positive very long.

12th of August 1944 50-mm prototype of recoilless rifle was shown in presentation held in Civil Guard Officer School. Not much progress had happened since tests done in July. By that time development of the prototype representing intended mass-production weapon was still under development and it was still intended to use the same varied inventory of largely modified projectiles as before. What was to change now was that the economic considerations and questions in what way this new weapon would fit to existing inventory of weapons and what new could it offer had started to surface. It is worth noting that basically all criticism concerning the weapon was related to its ammunition – either to how poorly it suited for this purpose, how much modifications it required or due to its poor availability.

Criticism that surfaced in August of 1944 noted that:

Projectile:

criticism:

50-mm mortar shell

No real improvement over existing 50 mm mortar.

50-mm flare for mortar

Ammunition availability near zero.

46-mm anti-tank rifle grenade

Poor accuracy, massive modifications required.

Panssaripanos m/42

Difficult to use, shape does not allow long range.

Panssarinyrkki F1 projectile

Effective range not likely possible beyond 125 - 150 meters.

Panssarinyrkki F2 projectile (*)

Same basic issues as with panssarinyrkki F1 projectile.

Smoke grenade

No real improvement over existing smoke throwers.

(*) 100-mm German Panzerfaust klein projectile.

(**) 142-mm German Panzerfaust 30 HEAT-projectile.

Adaptation of 50-mm mortar ammunition for this weapon was still incomplete and due to its higher rate of fire 50-mm mortar was often actually better fire support weapon than recoilless rifle. Some hand grenades had also been modified and tested for this weapon, but they required considerable modifications and since they were not Finnish-manufactured their further availability was uncertain. When it came to German 46-mm antitank-rifle grenades, their use in recoilless rifle demanded considerable modifications to projectile and after all development work done that far, the flight characteristics of this projectile were still simply terrible. And even if the 46-mm anti-tank rifle grenade would start performing as intended, its armor penetration was just 60-mm, which was too little to be effective. Adapting modified panssaripanos M/42 antitank-charge for the purpose had proved even more difficult, since due to its aerodynamically poor shape developing it as projectile with decent flight characteristics was just impossible. When it came to <panssarinyrkki (panzerfaust) projectiles both 100-mm and 142-mm versions had been tested, but they had proved problematic. Tests suggested that effective range of 100-mm projectile from panssarikauhu F1 / panzerfaust klein could be pushed to 125 – 150 meters, but not beyond that before shooting accuracy would drop beyond acceptable level. Panssarikauhu F2 / panzerfaust 30 projectile was notably heavier and because of this required much larger propellant charge to achieve similar muzzle velocity, the propellant charge needed for reaching good range would have resulted need for having structurally stronger (read: heavier) weapon. Otherwise F2 projectile had similar limitations as with F1. In addition adapting panzerfaust projectiles to this new recoilless rifle required extensive modifications to shape and structure of the particular projectiles.

Use with smoke (hand) grenade as ammunition did not really offer anything new, which the existing smoke throwers would not been able to provide and ability to use smoke ammunition in recoilless rifle was not considered as important that it would have warranted spending much resources.

17th of August 1944 Major General Svanström (Chief of Weapons HQ) presented doubts if the concept intended for the new 50-mm recoilless rifle was flawed. He noted that for the intended role as infantry support weapon for all soldiers to use the weapon would have to be easy to learn and able to gain trust of the common soldiers, or they would be unwilling to risk their lives by using it in battle. With its variety of modified projectiles the weapon was not exactly easy to use and the ad-hoc modifications in its ammunition were not exactly inspiring confidence. He noted that while the weapon was unsuitable as infantry support weapon with various types of ammunition, but if suitable ammunition would be developed and manufactured especially for it, it could be become a successful antitank-weapon. The next day Svanström also reported to Inspector of Infantry that Major Paloheimo should be given the opportunity to complete development of his 50-mm recoilless rifle, after which the weapon should be tested for the purpose of introducing it as antitank-weapon. At the same time he suggested developing of purpose-build new ammunition intended just for this weapon.

The development work continued and 29th of August 1944 two new prototypes were tested in Mikkeli airport. These prototypes built by State Rifle Factory (VKT) and Tolvan Oy were otherwise very similar, but their lock and breech mechanisms had structural differences, which did not effect to shooting performance of the weapon. As before available ammunition was modified projectiles, which apparently were mainly used for the purpose of trying to test what kind of shooting accuracy these new prototypes were capable producing. Even with their limitations this test with 50-mm mortar shells and modified 46-mm rifle grenades suggested accuracy good enough to hit tank-size targets most of the time from 200 and 300 meters. It is not known if the plan for developing HEAT-projectile especially for this weapon ever started before Finnish recoilless rifle were terminated, or if this development work had any impact to antitank-rifles developed in Finland in 1950's.

Major Paloheimo wasn't alone in developing this weapon. Year 1944 he and engineer Tuomola filed patent application number 3456/44 to Finnish patent office for recoilless rifle and the venturi nozzle system used in it. Later when Finnish military awarded him with reward of 9,000 Finnish Marks for his development work with recoilless rifles, he asked the reward to be split in three parts, which were rewarded to him, engineer Saarento from State Rifle Factory and draftsmen Narinen, who had apparently made the blueprints. Finnish Armed Forces respected his wishes and rewarded the three persons each with 3,000 Marks.

It must be noted that ultimately this recoilless rifle development project produced very little results, but this was for the large part because Finnish military failed to understand early on, what would become the main use for recoilless rifles and did not start the development from recoilless rifle ammunition instead of recoiless rifle. The attempts to modify existing ordnance in such manner that it would work with the recoilless rifle showed maybe skills of improvisation, but did not produce ammunition needed to for it. Is has to be noted that apparently the Finns come up surprisingly good propellant for the purpose. The Germans used black powder as propellant in their panzerfaust recoilless rifles, last of which apparently did not achieve maximum effective range any better than the last Paloheimo's 50-mm prototypes.

Finnish Army continued to use panzerfaust and panzerschreck until late 1950's, at which point they were replaced with 55 S 55 (55 mm recoilless rifle model 1955) light recoilless rifle. This Finnish-developed recoilless rifle had two types of ammunition - high explosive antitank (HEAT) projectiles for antitank-work and high explosive (HEAT) ammunition soft targets. At this time it remains unknown if the prototypes developed in 1944 played any role in development of 55 S 55.

 

PICTURE: Finnish rocket launcher prototype installed on gun carriage of Soviet 45-mm antitank-gun getting tested. Photo taken in Tyrvää March of 1944. The series of photographs suggests that the projectile was a rocket of sort. This was likely one of the Ordnance Department prototypes. (SA-kuva photo archive, photo number 147539). CLICK THUMBNAIL TO SEE LARGER PIC (127 KB).

105 mm recoilless rifle prototype designed by Ordnance Department

(Taisteluvälineosaston 105 mm reaktioase-prototyyppi)

This was a 105-mm recoilless rifle prototype designed by Ordnance Department of Finnish Armed Forces General Headquarters. Very little is known of the prototype, since it is only mentioned in some documents. Presumably it was larger-caliber alternative designed for recoilless rifles prototypes developed by Major Paloheimo for the same organization around that time.

Reports suggest that the inspiration for this development originated from US bazooka and German panzerschreck and the development work started sometime late 1943. The apparent main goal of this development work was to develop recoilless antitank-weapon with larger effective range than panzerfaust and panzerschreck. They also reveal that first prototypes existed 21st of March 1944, but that time it was still unclear if the weapon should be a rocket launcher or recoilless rifle, so prototype of each type was under development. The recoilless rifle version prototype was to 105-mm caliber, weight 15 – 20 kg and capable firing projectile weighting 4 – 5 kg with muzzle velocity of 120 – 150 m/sec. The rocket launcher version prototype on the other hand was to be 100-mm caliber, weight 20 kg and capable firing 5 kg. However the report noted that there was development problem with propellant charge (430 grams of gunpowder) needed for rocket launcher version prototype, since the propellant was burning in uneven manner. 105-mm recoilless rifle was to be equipped with rifles barrel, while barrel to be used in 100-mm rocket-launcher prototype was to be without rifling. One of the reports mentions also 90-mm recoilless rifle prototype, which was under development in late April of 1944, but since it is not mentioned in later documents its development work probably ended before even reaching prototype stage.

By 18th of August 1944 105-mm recoilless rifle prototype had recently been completed and was about to be tested soon. Apparently the idea of 100-mm rocket launcher prototype had been abandoned by that time with development work now concentrating to 105-mm recoilless rifle prototype.

Technical specifications listed at that time:

The prototype had mechanical firing system and pressure level of about 1,000 – 1,1000 atm. It was intended to fire high explosive antitank (HEAT) projectiles with expected to have armor penetration of about 120 – 150 mm. Two sorts of ammunition had been ordered for this prototype, light and heavy version, with 50 rounds each. At that time delivery of this test ammunition was expected to happen within next 10 days. Report also noted that weight of the weapon could be probably reduced before going to next development version.

Report dating 7th of November 1944 indicates that the prototype had been tested in ballistic laboratory with the earlier mentioned two sorts of test ammunition and test results indicated that:

Weapon’s chamber pressure with both projectiles was about 400 kg/square centimeter. The test was considered success and the further prototypes with their weight reduced about 16-kg were to be ordered from State Rifle Factory (Valtion Kivääritehdas / VKT). Next batch of test ammunition was to be with projectiles weighting about 3.5-kg and with expected muzzle velocity of about 130 m/sec. This new ammunition prototype was about to be test-fired about two weeks later. It remains unclear if this batch of ammunition was ever tested, since apparently the whole project was probably soon stopped by Soviets in the Allied Control Commission with forced shutdown of Finnish weapons development.

Finnish military didn't come up with heavy recoilless rifle until introduction of 95 S 58-61 (95 mm recoilless rifle model 1958-1661) developed in late 1950's. This recoilless rifle equipped with both HEAT and HE ammunition have remained in use of Finnish Army to this day. It remains unclear if the prototypes developed in 1944 played any role in its development.

 


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