wz.35: Poland’s Remarkably Misunderstood Antitank Rifle

Polish wz. 35 ATR

by Leszek Erenfeicht

In 1929 Maj. Tadeusz Felsztyn [TADEUSH FELSHTEEN], Scientific Director of the Central Shooting School in Torun (a chief firearms research and instruction institution in Poland between 1919 and 1932, leading all small arms related R&D as well as army’s small arms instructor training) took interest in the German Halger (Johann Halbe & Hermann Gerlich) high-velocity sporting rifles, showing extraordinary performance with small caliber bullets propelled at extreme velocities against armor plates. Halger rifle was bought, and tested in Oct., 1931, upon which a decision was made to start developing in earnest a Polish own AT and AA weapon, shooting small-caliber bullet with high velocities. It was decided to start with non-automatics and see where would that lead. Felsztyn was sure that velocities of 1700-1800 mps can be reached with a 7.9 mm service bullet, achieving piercing performance sufficient to make it a viable AT weapon. The State Powder Factory was ordered to develop powder able to propel the SC (sS) ball at 1200-1400 mps for starters, while the State Rifle Factory was ordered to develop and build an “Initial ATR” in 7.9 mm, as a starting point towards an “Objective ATR” of 10-13 mm caliber, and then towards semi-automatic or even fully automatic weapon (HMG-type), should there be a need for one.

In 1932 three experimental cartridges were developed, all in 7.9 mm caliber, all three cases rimless. One had a 80 mm long case with 15.44 mm rim diameter, the other was 86 mm long with 15.88 mm rim diameter, then the third one 92 mm long, the rim diameter identical to the service round (11.95 mm rim). These all are known mostly from the reports, and unprimed cases that survived for the first two. Full testing report survived only for the 92 mm round. The weapon firing it, based on a regular Mauser 98 rifle, was designed by Cpt. Edward Kapkowski, and it was shot on Feb 19, 1932. Firing at 15 mm armor plate at 100 m with a lead cored S bullet, @90 deg impact angle, at an initial velocity of 1113 mps, gave 100% repeated perforations, tearing out a steel plug of 15 mm diameter from the plate – and so did in the test with 15 mm plate @ 60 deg. At 1073 mps the plug also formed – but the energy was insufficient to fully separate it, and it only protruded from the rear of the target.
Fired at a 25 mm plate, the lead-cored S bullet with 1111 mps initial velocity left a 10 mm deep crater but failed to perforate. Experimental S bullet with steel core also failed to perforate the 25 mm, damaging the armor plate even less than lead bullet. While firing at a 15 mm plate @ 45 deg @ 100 mm, instead of a perforation, the bullet tore a piece of armor 10 mm in dia. and 4 mm thick, then ricocheted. In another test, a 5 mm iron witness plate was placed 1 m behind the 15 mm armor plate at 100 m @ 90 deg. Upon impact, the front plate was pierced clean, while the rear one got severely mauled (no perforation, but a 3 mm high mound was protruding from the rear surface). Upon investigation it was established that the damage to the witness plate was done not by the remnants of a bullet, but by a plug of armor steel torn from the front plate by the lead-cored bullet. The bullet itself disintegrated upon impact and did not penetrate the armor in any of the tests. No 25 mm plates were pierced, and a slight change of velocity or angle was able to prevent the bullet from piercing even the 15 mm plate. All in all, several dozen shots were fired with a rifle, with no visible damage found upon the post-firing examination in any of the parts exposed to the pressure and friction (barrel, bolt, receiver).

In the same test the standard P (SmK) projectile only dented a 15 mm plate at 100 m, while Halger .280HV as much as scratched it with muzzle velocity of 1180 mps and left a slight discoloration @ 1050 mps velocity.

Basing on the trial results, target performance minimum for the future ATR was thus set at piercing 15 mm @ 200m and 20 mm @ 100m. In May, 1932 the Infantry School commander, Col. Bruno Olbrycht proposed that the ATR program be limited to rifle-caliber phase, as the large caliber would be “a bridge too far” with the current technological abilities of the country’s industry. His proposition was to concentrate at what has already seemed to be within reach, perfect it, adopt it, manufacture, stash aside a suitable amount for mobilization – and only then go another hop, to avoid aimless throwing around and chasing wild geese.

In 1932 a decision was made to move the R&D work from provincial Torun closer to the capital Warsaw, where a new Ballistic Research Center in Zielonka has been established. Felsztyn was promoted to LtCol and transferred to the new establishment, where he became the ‘ATR tsar’ or ‘ATR kingpin’ if you like, by forming a liaison between the ammo team at the State Ammunition Factory in Skarżysko (between Radom and Kielce, some 140 km from Warsaw) and the rifle team at the State Rifle Factory in Warsaw. Both were top secret, and so were not allowed to contact directly, and Felsztyn became the only person, who knew the program from both ends. Fortunately he proved enough of an expert to shoulder that burden successfully.

The State Rifle Factory came up with two test rifles. One designed by Antoni Karczewski, the technical director of the company. Not only did it prove not able to shoot the bullet straight (the rifling was wrongly matched to the bullet and it sheared material from the bullet, instead of imparting rotation – as a result bullets were ruined in bore and erratic in flight, if not disintegrating upon leaving the muzzle). Plus, his rifle was over 16 kg heavy, and set with a hydropneumatic barrel return mechanism. The other rifle was a project submitted under the cover name Uruguay by a young engineer Jozef Maroszek [MAROSHEK], who built a slightly oversized (sturdier and with longer barrel and bipod) service rifle fed with exchangeable magazines, weighing in at around 10 kg – just like the BAR wz.28. The bolt design was taken from his earlier rejected KP-32 infantry carbine. This bolt only comprised six parts: body with lugs (two symmetrical at the front end plus a safety lug at the rear), one-piece extractor, the main spring, firing pin with recock/safety ring (Swiss style), firing pin sleeve and the mainspring support sleeve. The design made it extremely resilient while compact and lightweight. Being a young man, he pursued bold, novel ideas, and made a short work of many ‘sacred cows’, including the hoary barrel resilience formulas. Instead he used the newest American methods and his calculation showed that a much lighter barrel was enough to withstand the pressure of the new ATR ammo. Instead of the complicated recuperator, he put a single baffle muzzle-brake, able to reduce the recoil by astonishing 60%, reducing the kick to slightly more potent than the regular rifle’s.

At that point, the rifle was still chambered for the 7.9 mm x 86 round, which proved to be problematic. The performance with the new rifle was nothing short of convincing: 20 mm plate @ 100m @45 deg. The problem was, that the new rifle ate barrels like hotdogs: they were written-off after just 60–70 shots! The problem was a mix of progressive and fast-burning powders used in that round. There are no hard evidence as to what was the exact propellant load used in the final 7.9 mm x 86, but the testing minute of the 7.9 mm x 92 mentioned a 50/50 mix of Halger powder with regular S-ammo powder. Now that it seemed that the rifle was finally nailed, it was rushed into production with an order of three spare barrels each, to cover for the 250 rounds which were to be allocated with each rifle. Rifle was prepared for it, designed so that with an individual set of tools the barrel could be exchanged by a single man in field conditions. Each barrel had its own sights mounted on it (a dove-tailed notch set for 200 m and a dove-tailed front sight blade), so that once zeroed, they needed no re-zeroing after exchanging. The barrel was not exactly a quick-change one and its changing was not exactly a battlefield job, but still to exchange a barrel on a Maxim or Browning water-cooled machine gun you also needed to detach most of the parts – and yet it was considered a regular maintenance chore.

While the production of the rifle was preparing, the ammunition development did not stopped. In 1934 the ammunition team came up with a completely new round, in a special case 107 mm long, with a 16.9 mm rim diameter, and loaded with a new bullet, called DS. The length and weight of the projectile were similar to the heavy bullet SC (sS) at 34.35 mm and 12.8 gram, but they were clearly differentiated by the external shape – the SC being a boat-tailed bullet, while the DS was cylindrical at the base. The bullet core material was lead with 2-3 % antimony, exactly the same as for the ball ammunition. The lead core was encased in a CNCS (cupro-nickel clad steel) jacket. The round was loaded with a charge of 10.78 – 10.82 g (measurements taken from about dozen rounds, manufactured 1936 to 1938, with their bullets pulled) of new X-27 graphitized nitroglycerin powder in form of cylindrical grains 1.6 mm x 3 mm, each with three flash holes. This powder was formulated and made by the State Powder And Explosives Factory in Pionki.

This new round was a breakthrough. The performance was even better, the muzzle velocity was measured at 1270 to 1300 mps, and test minute reports 20 mm armor plate perforated at 100 m (no angle stated – but even at 90 deg it met the requirement) with a 25 mm dia. plug formed. The 15 mm plate was perforated @60 deg at a distance of 300 m, which was deemed the limit of practical aimed fire distance. A plug of 20 mm dia. propelled from the plate then perforated a 40 mm pine witness board placed 1m behind the plate – illustrating the wounding potential of such secondary projectile. As previously, no evidence was found of the projectile fragments behind the plate, the bullet itself did not penetrate. The experts came up with an explanation to the phenomenon: the kinetic energy of the bullet was so high, that when it was imparted onto the plate’s particles, it gave them speed, at which their own kinetic energy exceeded the bond, keeping the plate together – similar to what happens after the shaped-charge hits the plate, but at a much smaller scale of course, because there were no explosives used. Gerlich called that ‘quasi-explosive action’ of his bullets against the armor. The plug thus torn from the plate impacted upon the crew or mechanisms behind, and when it missed and impacted upon the insides of the armor, it still had enough energy to spall, bouncing a cloud of secondary splitters flying at random, dangerous to the crew, fuel lines, control and electric cables, etc. The surviving plugs collected from the former R&D firing range of the ammunition factory were of between 18 to 29 mm in diameter and weighing in between 30 and 56 gram, so there clearly was a plenty of material to disseminate.

The rifle was also perfected. Calculations proved that the barrel should be extended by 20%, from 1000 to 1200 mm. That, coupled with the new ammo, did miracles for the service life of the barrel, which was extended 350-400% almost overnight, from 60-70 to 250-300 shots, which in itself all but eliminated the need for spare barrels, resulting in a sharp reduction of the already placed order for these – while the ammunition allotment was increased fourfold, from 250 to 1,000 rounds. As there was to be one ATR per platoon, or three in a company, a former individual container with three spare bbls now became a company one. The spares were now regarded truly as spares: only needed if a regular barrel was damaged, or fired 200 rounds – after which the swap was mandatory, as per the manual. The arrangement, in which rifles were serialized in one range, and barrels in the other, was left intact as well – so the wz.35 has legitimately two serials, one for the rifle, and the other for the barrel. The barrel exchange was now considered a repair, not routine maintenance, and the manual reserved it for the battalion armorer, as all other repairs.

At that time, early in 1935, the performance target achieved by the ATR was still effective enough against most already deployed tanks and armored cars. The future was murky, though, as the most armies (including the Polish Army) was already planning to deploy heavier and better protected tanks. Some of the army command opposed commissioning the ATR for that matter, and demanded their performance improved by at least 50%. That would in fact necessitate the re-starting of the work and only promised better results at some point in the future – while the army was still left vulnerable to the enemy armor. Eventually the multiple-stage approach was taken, and on Nov 25, 1935 the Maroszek ATR was introduced into the army as the ‘Rifle, 7.92 mm, Model of 1935’ – carefully avoiding in this moniker any clues as to its anti-tank nature. The program was top secret, even the venue where the rifles were manufactured was not the main compound of the State Rifle Factory at Dworska Str., but the Zbrojownia Nr 2 (ZBROYOVNIA No2) at Szwedzka Str in Praga – the part of the capital situated on the “wrong” (eastern) side of the bisecting Vistula River. The Zbroyovnia was the former ammunition factory (before that was moved to Skarżysko in 1925) then a repair facility, where also most of ‘hush-hush’ projects were performed, including the semi-automatic rifle work later on.

The first order for 1000 ATR was placed in Dec 1935, with the delivery scheduled by March 31, 1937 (end of FY 1936/37). But as of Jan 1, 1937 still not a single rifle was delivered, because of the difficulties the Zbroyovnia had ran into. 450 were to be ready by 1 Apr, with the rest delivered by Jun 15. The ammunition was being manufactured as of 1936. 7,629 ATRs were needed in the Phase One (i.e. immediately) and a grand total of 20 187 ATRs were planned to be purchased in both phases (until FY 1940/41), at a cost of 1,000 Polish zloty (5.14 zloty = 1$ in 1937) per rifle with equipment & spares and 960 zloty for its ammunition supply (1,000 rds per rifle). For comparison: standard wz.29 infantry rifle (Mauser-98 style) costed at the same time 170 zloty, but the wz. 28 BAR costed 2,014 zloty.

At the end of the Phase One (scheduled originally in FY 1938/39), the Polish Army was to deploy 1 rifle per platoon, 3 per infantry or cyclist company / 2 per cavalry company, 9 per infantry battalion, 27 per infantry regiment / 8 per cavalry regiment, with additional ATRs in reconnaissance squads. With 36 Inf Divs and 40 Cav Regts, the active Army was to have 3,236 ATRs with the rest in training establishments and mobilization reserves. In Phase Two, until 1941, the issue was to be trebled in the active army, with 9 ATR per company and 3 per platoon (i.e. 1 in each squad, same scale as LMG).

At the same time R&D continued, with the new 10 mm x 99 ATR round being developed in 1937/38 with a new rifle to go along with that. This round was based on 13.2 mm x 99 Hotchkiss ammunition for the then regulation HMG of the Polish Navy, for which rounds were made by the Skarżysko plant, as well. The 10 mm case used the body shape of the Hotchkiss case, but thicker at the head, necked down to 10 mm and fitted with a rifle-sized primer instead of the large-diameter HMG primer. Another project in progress at that time, also vaguely based on Hotchkiss round components was the 13.2 mm x 181 cartridge, being twice the length of the regular 13.2 mm Hotchkiss HMG case with a regular 13.2 mm bullet and a large, 25.9 mm rim dia. Nothing more is known about this latter cartridge – the only specimen known found its way into Woodin Laboratory in AZ with the Polte Magdeburg prototypes collection, labeled only “polnisch” (Polish) with no further data.

Neither of the latter was fielded as an ATR, though, because in 1938 the new AT & AA automatic cannon (chambered for the 20 mm x 138B Solothurn round – same as used by the Finns in Lahti L-39 or by the German Flak 30/38 program) was initiated, to replace the ATR program eventually as of 1941, along with the 47 mm long-barreled AT cannon augmenting then replacing the 37 mm Bofors wz.36.
In April of 1939 the wz.35 rifles were distributed from the central storage in Warsaw’s Citadel to the regiments, and – they being still top secret weapons – the crates were misleadingly labeled as optical surveying equipment. A longest crate (1,780×270 x 183 mm, labeled ‘Surveying Equipment A.R. I’) contained a single rifle with barrel installed, while the shorter one (1,250 mm, ‘Surveying Equipment A.R. II’) contained 3 spare barrels (supply for one company), and the shortest of them (‘Surveying Equipment A.R. III’) held barrel exchanging tools and other spares (firing pins, mainsprings) for the battalion armorer. Ammunition (288 rounds in two zinc-plated tins of 12 cardboard boxes each holding 12 rounds) were packed in a crate labeled ’21 K. Eksport’. The regimental commanders were informed (in verbal form, leaving no written traces) of the nature of the supplies and ordered to select 2-3 marksmen from each platoon – but were to inform them of their task only after receiving instruction to open sealed envelopes containing orders and manuals, which were distributed to the regimental HQs. The fact of distribution allows us to guess, that at least the Phase One active army allotment had to be manufactured by that time.

The order to open the sealed envelopes came in mid-July, authorizing the regiments to open one each of the crates and give each battalion a secret demo, during which battalion and company commanders and the 3 best marksmen per company got an opportunity to get acquainted with the new weapon and fire a few shots at a 200 m distant targets. All cases were to be collected, replaced into the ammo crate and the crate itself re-sealed. All participants of the demo were sworn to keep it secret. The battalion armorer (no assistants allowed) was then to clean and maintain weapon, change the barrel to get the hang of the procedure, and then to put the equipment away, back into crates, have it re-sealed and put back into the regimental armories.
During the night of Aug 27/28, 1939 an order was sent to open the crates again, this time all of them, and distribute the rifles and ammunition to the selected platoon marksmen, with two additional rifles per each recce platoon (in each regiment there was one mounted on horses, and the other on bicycles), thus each infantry regiment had 29 ATRs, instead of 27. The individual ammunition allocation was 24 rounds in two cartons ready ammunition, fitting in a BAR magazine pouch – meant to be the 2-days’ supply – per man, while the rest were packed with the company and battalion ammunition columns, each with additional 24 rounds per ATR, for a total of 72 rounds – or half the zinc box – per capita (or 6 days’ supply). Unfortunately, some units, e.g. 30th Inf Div, had already deployed from the garrison, and they had to send people back to take the crates from the garrison, which postponed the delivery of the weapons. This one unit had left a paper trail of such occurrence, but how many more had similar problems is unknown, due to lack of records.

Was the secrecy around the ATR excessive (even “pathological”), as it was maintained by the post-war (mostly the red-tinted) historians? Well, it depends. It is definitely a myth, that the secrecy wasted the effect, affecting the efficiency, for the shooters were not trained with them. C’mon, if you are a military-grade trained user of a Mauser 98 style weapons, proficient enough to become selected as a designated marksman, what has this rifle so new and unknown, that you need more than an hour transition period to read the 6-page manual and handling the weapon to master it? At 200 m no one can miss a tank-sized target from a 4-foot barreled rifle. The recoil was naturally stouter than with a service round – but then, the big-game rifles with Magnum ammunition develop a similar kick, and no shooter drops dead from it. Some even relish the experience…

On the other hand, the presence of the ATR in 1939 proved an unpleasant surprise to the Germans, and there were numerous relations, even in wartime published propaganda books, as to the extent of the damage done with it. But was it enough by itself to stop the Blitzkrieg? Of course not – other than the Russian Winter prior to 1944 there was not a force present in Europe capable of defending against the Germans advancing by land. Especially not with the Soviets stabbing Poland in the back on Sept 17, 1939, and occupying 54% of its prewar territory. But after Polish campaign and before the attack on France, all PzKpfw I and II light tanks, still a mainstay of the Wehrmacht’s armor, were up-armored to a minimum of 20-25 mm, and that was done within just a few months. Had Germans know about the Polish ATR and its performance beforehand, they could have easily done it earlier – denying even what modest damage was done to them with the ATRs.

How many ATRs were made? No hard proof is available, but the Phase One target was to be completed in FY 1938/39, i.e. by March 31, 1939 – and as we remember, the rifles were distributed to regiments in April, meaning they had to be present or accounted for at the scheduled date. In Oct 1938 2000 were reported delivered. We can assume then, that at least the active army allotment of ca. 3,350 rifles (incl. the extra 2 rifles per infantry regiment) were ready, with probably the rest also delivered, with possibly some percentage of the Phase Two, as well. For the surviving weapons, serial numbers as high as 6588 were reported – rifle serial number, that is, not barrel, as these were serialized in a separate range, and serial numbers run as high as 15558 (which is, BTW, the s/n of the barrel attached to rifle s/n 6588 – displayed in the Polish Army Museum, Warsaw).

Nobody knows what have happened to them, though, as the Germans only report capturing 880 Polish ATRs with 255,000 rounds of ammunition – but only 650 serviceable barrels (surrendering troops mostly hid these or bent the barrels, levering them between tree branches). The availability of barrels limited the amount used in the French campaign to 630 – which still is a sizeable amount, there were perhaps even more of these than they had their own PzB 38 and PzB 39s in May, 1940. It was designated at first the Panzerbuchse 35(p), and later on PzB 770(p). After that, in January 1941 250 rifles were sold to Italy, resulting in the “Fucile controcarro Modello 35(p)”. After Italian surrender some were recaptured and labeled PzB770(i). Despite their own 1939 experience, the German did not believe in lead-cored AT round capabilities, and so they redesigned the Polish round, fitting it with a tungsten carbide-cored bullet from their own 7.9 mm Panzerbuchse 38 and 39. The original Polish ammunition stocks were designated training ammunition or re-built with German bullets. Later on they came up with a special bullet, the 14.55 gram Geschoss 318 o.Rs. (ohne Reizstoff), lacking the lachrymatory element present in the regular black-tipped Geschoss 318. The reloaded cartridges were given a red primer annulus (original Polish was green). Later on, in 1940, manufacturing of the German 7.9 mm x 107 cartridge cases with larger diameter German PzB primers started at the HASAG Hugo Schneider AG, Werk Altenburg, Thüringen, coded ‘BK’, then ‘P490’, and finally ‘wg’. The ammunition itself was loaded by the company Theodor Bergmann & Co KG, Werk Velten (coded ‘cdo’). The cases are dated in both 1940 and 1941, but surviving cartridge box labels are all dated in 1941 – probably relating it to the Italian contract. The Italian manual identifies ammunition as “having a black tip”, which probably means that no Polish ammo was delivered with the Italian contract.

Some ATRs were taken by the Polish troops who crossed the Hungarian border after Sept 17 and got interned there to avoid Soviet captivity (the Katyn Forrest massacre proved them right). The troops were mostly allowed to seep through to France, where the émigré government was organizing the new Polish Army, but their weapons stayed in Hungary, with many of these eventually sold by the Hungarians to the Finns. The Finns did not believe in rifle-caliber ATRs, though and they only used these as training weapons, while the front troops were armed with British Boys Mk I Rifle and then Soviet PTRS/PTRD-41 ATRs. And moreover – the times have changed, and with them the enemy armor. Even in the early days of the Continuation War in 1941, only the older T-26s and BTs were marginally vulnerable to the 8.00 mm pst.kiv./38 (as the Polish ATR were called in Finland) – but then, with the advent of the T-34 it was all over for them, and Pzf 30m (gr) became Finnish favorite individual AT weapon.

How many did the Soviets capture, we will never know, but the main mobilization warehouses were placed in the Soviet-occupied zone, where possibly the rest of the ATRs from Citadel were taken in April 1939. At least the impact of the wz.35 was immediate, kick-starting the Soviet ATR program. The first Soviet ATR, the 12.7 mm Rukavishnikov’s muzzle brake was an almost dead-banger on the Polish design, while Polish rifle was illustrated in foreign weapons and ammunition manuals, as well as detailed analysis (including construction drawings and pressure curves) were prepared for the students of Soviet military academies.