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Karabin wz. 35: Secret Weapon of Rzeczpospolita

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One of the most popular themes in anti-tank defenses during the interbellum period was the development of anti-tank rifles. Designers had several approaches to this issue. One was the use of "cannon" calibers of 20 mm, or even 24 mm, with a relatively heavy bullet and a lower muzzle velocity. The other approach was to increase the muzzle velocity of a regular 6-8 mm rifle bullet. The wz. 35 anti-tank rifle was a product of the second approach.


Hermann Gerlich is one of the most famous engineers among those who was designing low caliber anti-tank rifles. His 6.5 mm rifle, designed in late 1920s, had a muzzle velocity of 1400 m/s (compared to 900 m/s on a regular Mauser rifle). This boost gave phenomenal results. A lead core bullet made a 15 mm wide hole in a 12 mm armour plate. A regular rifle bullet made only a 2 mm dent when hitting the same target. Interestingly enough, Gerlich's bullet did not penetrate the armour. It shattered on impact, but punched a "cork" out of the armour, which would then ricochet and cause damage inside a tank or an armoured vehicle. This phenomenon was dubbed the "Gerlich effect".

Gerlich's work was not secret, and was widely discussed in specialized literature. In Poland, Colonel Tadeusz Felsztyn of the Central Rifle School in Torun, and a prototype of the Gerlich rifle was tested there in 1929. In later years, Felsztyn deemed it necessary to develop a small caliber anti-tank rifle, and managed to gain the interest of both the army and entrepreneurs. The gunpowder factory in Pionki invested 10,000 zloty of its own funds into the development of appropriate nitrocellulose propellant (its grains had three channels in them to increase the surface area). The munitions factory in Skarżysko developed a casing that could hold 50% more pressure than a regular rifle round. The main role in the development of the new weapon was played by the designers of the Armaments Research Institute and Warsaw rifle factory.

Design

The development of the design was given to an employee of the Armaments Research Institute, Józef Maroszek (a graduate of the Mechanical Faculty of Warsaw Polytechnical). Despite his youth, Maroszek had a reputation of a talented design engineer. Felsztyn described him as a "young engineer, talented designer, full of youthful enthusiasm, and some kind of mysterious instinct and ingenuity". 

 Józef Maroszek in the early 1930s.

Maroszek's weapon was simple and relatively light. The rifle fired 7.92x86 mm rounds with regular SC bullets. At 100 m, the bullet put a 20 mm hole in a 20 mm plate at a 30 degree angle. However, even initial trials revealed a problem: a rapid deterioration of the barrel. After several dozen shots, it was completely useless. Several years were spent trying to correct this flaw. By 1935, the lifespan of one barrel increased to 250-300 rounds. Considering the purpose of the weapon, this was entirely acceptable. This was achieved by increasing the barrel length from 1000 to 1200 mm and changing the design of the bullet, which received a longer cylindrical section (this stabilized the path of the bullet in the barrel). The round was completely redesigned, and the new round was designated 7.92x107 mm DS. The round weighed 61.51 grams, 12.78 of which was the bullet. Modified rifles went through trials successfully. At 300 meters, the new bullet knocked out a 15 mm plug out of a 20 mm plate.

A regular Mauser round (bottom) and a DS round (top).

The rifle was accepted into service under the name Karabin wz. 35. In Polish, a rifle is called "karabin", and what we refer to as a carbine is called "karabinek". The name had no indication of the rifle's anti-tank purpose. Polish command was afraid that if word of the weapon's capabilities gets out, Poland's enemies would thicken the armour of their tanks.

Overall view of the Karabin wz. 35.

The Karabin wz. 35 was a magazine-fed bolt-action rifle. The sliding bolt locked with three symmetrical locking lugs. The barrel was removable, and screwed into the breech. The barrel was replaced after 200-300 rounds, but this could only be done in a weapons workshop with special instruments. The barrel had six right-hand rifling grooves, a muzzle brake that consumed 65% of the recoil energy, and a bipod that folded up forwards. The removable box magazine fit 4 rounds and locked in with two springs in the front and the rear, which meant that replacing the magazine required the use of both hands. The open sights were calibrated to 300 meters. The stock was made out of hazelwood. A small wooden top covering protected the shooter's hands. A leather carrying belt was attached to two loops.

Production and distribution

Five preproduction rifles were produced at the end of 1935 and start of 1936. Mass production began a year later at the Warsaw Rifle Factory, where the secret "Ur" shop was organized. Colonel Tadeusz Pełczyński, the head of intelligence of the Polish General Staff, came up with this name. In his opinion, it would make it seem like the shop was producing weapons for Uruguay. Modern Polish researchers consider that barrels came from another Polish manufacturer, but it is not known which. This is a good illustration of the secrecy that surrounded the new weapons. The munitions factory in Skarżysko also took measures to keep its secrets. The bullets were produced in the general production area, but the rounds were assembled in a special shop with restricted access.

Overall, the orders totalled 7610 rifles, and 2000 of them went through military acceptance by October of 1938. The overall number of rifles produced is estimated at 3500-3600. This was enough for a peacetime army, but without a mobilization reserve. Considering that a number of weapons remained in the warehouses, many units of the Polish army did not receive anti-tank rifles by the start of the war in September of 1939.

The weapons were shipped in sealed wooden crates labelled "measuring equipment" and numbered 1 through 3. Crate #1 (178 by 27 by 18.3 cm) contained the rifle itself and the manual. Crate #2 contained three spare barrels. Crate #3 contained the instruments required to change barrels, as well as spare parts. Ammunition was supplied in crates labelled "21 K Export". Each crate contained two sealed zinc boxes with 12 packs of 12 rounds each, containing 288 rounds in total. The anti-tank rifleman carried 24 rounds (6 magazines) in two burlap bags designed for the Browning wz.28 machinegun.

A cardboard package for 12 DS rounds.

The weapon's supporter, Colonel Felsztyn (who retired in the late 1930s) considered that this weapon had to be introduced into every squad. High command decided otherwise. Three rifles were issued per company (one per platoon), and two more in the regimental reconnaissance company (one for the bicycle and one for the horse platoon). An infantry regiment had 29 rifles, and a cavalry one had 13 (three per squadron and one in the bicycle platoon).


Carrying the Karabin wz. 35 on foot.

It was only permitted to open the boxes with "measurement devices" on orders from the Minister of War. Such orders were distributed on July 15th, 1939. They instructed that a limited number of personnel be familiarized with the weapon: three riflemen from each infantry company or cavalry squadron, one armourer, and the commanders of companies, squadrons, battalions, and regiments. The process included one or two series of firing at targets 200 m away, using no more than six rounds per company/squadron. After that, it was instructed that the rifle be put away into its crate and resealed. The spent casings were to be put away into the ammunition crate, and also resealed. Naturally, this kind of "instruction" would give the riflmen only the slightest idea about the weapon they were going to fight with.

Carrying the Karabin wz. 35 on horseback, view from the side.

Carrying the Karabin wz. 35 on horseback, view from the rear.

Carrying two Karabin wz. 35 rifles in a horse pack.

Use in battle

Works examined by the author have no mention of any kind of orders to issue the Karabin wz. 35 as a result of the mobilization. Polish researchers considered that the weapons were issued independently by division, brigade, or even regiment commanders. The most eager gave the order on August 31st, 1939, others waited until the first days of the war. Information regarding the use of the weapon in combat is scarce, but one can state with some certainty that the weapons were effective in battle with German light tanks and armoured cars. A soldier of the 67th Tank Battalion of the 3rd Light Division wrote:
"We have been fighting for two hours... We see anti-tank rifles, their fire puts holes in our armour. We squeeze the triggers of our machineguns without rest and see men and horses fall in the spray of fire. There is only one rule here: us vs them. Our tracks churn up the dead and the living, holding out until their last breath. Despite all this, Polish artillery and anti-tank defenses fire with unchanged fury. Fountains of soil spring up between the tanks. Sparks flash often as bullets hit armour..."
The effectiveness of  the anti-tank rifles in the Polish campaign relied entirely on the will of the commanders and soldiers. Where the units did not panic, the Karabin wz. 35 was used effectively until the end of the fighting, or at least until ammunition ran out. Even though no instructions regarding the use of the anti-tank rifle reached the soldiers (again, because of the secrecy), commanders with initiative had to figure out how to use the weapons on the go.

There is evidence that the Karabin wz. 35 was used in mixed formation alongside the Bofors wz. 36 cannon, in which case the anti-tank rifles were placed to finish off the tanks that broke through the artillery fire. There are also frequent mentions of using the anti-tank rifle from ambushes, firing into the enemy's flank. Riflemen were sometimes put out ahead of the main line of defense in tank-likely directions, where they were covered by machinegun fire. The commander of the 21st Infantry Regiment, Stanislaw Sosabowski, wrote about the fighting at Chrostowo Wielkie on September 3rd:
"Our anti-tank weapons are perfect, both the cannons and the rifles... The soldiers began to trust their anti-tank rifles when it was shown that they could immobilize a tank from 100 meters away."
Practice showed that the brief period of familiarization with the anti-tank rifle did not significantly impact their effectiveness in battle. The Karabin wz. 35 was simple to use, and the commanders gave them to their best riflemen, which manged to figure things out as they went. A much bigger issue was the assignment of just one soldier per rifle, rather than a crew of at least two. This meant that the rifle would almost certainly be lost in case of the soldier's death. Another issue was the lack of any indication that the bullet hit its target. The bullets of the Karabin wz. 35 had no tracers.

Despite the effeciveness against light armour, the Karabin wz. 35 was not a wonder-weapon that could save Poland from defeat. Could these weapons be used more effectively? Likely yes, but they could still not resist concentrated attacks by the Wehrmacht's mobile forces.

A Karabin wz. 35 among other Polish weapons captured by the Wehrmacht.

A significant amount (at least 900 units) were captured by the Germans. The weapon was adopted under the index PzB 35(p) and used during the Blitzkrieg in the West in the 1940s. Polish ammunition was reloaded with P318 tungsten-cored bullets, the same type as used in the PzB 38 and PzB 39. The muzzle velocity increased from 1270 to 1295 m/s, but the barrel wear also increased. With a sufficient number of the PzB 39 rifle, the Germans did not use the Karabin wz. 35 further, passing 630 of them onto Italy. These rifles were used in North Africa, on the Eastern Front, and even in Italy itself under the name Fucile controcarro 35(P).

American soldiers examine a captured Fucile controcarro 35(P) with interest. Italy, 1943.

A small number of Karabin wz. 35 ended up in Hungary along with retreating Polish forces. In March of the next year, the Hungarian government sold 30 rifles to Finland. The Finnish army used them under the name 8 mm pst kiv/38. They were used against the Red Army in 1941, but were soon removed and sent to storage due to a lack of ammunition and spare parts. After 1956, about 15 of the rifles were sold to collectors in the United States.

Finnish soldiers with a 8 mm pst kiv/38.



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