page_title: Ckm wz. 30
section_title: Modifications
hierarchical_section_title: Ckm wz. 30 / Modifications
caption_attribution_description: Polski: Pokaz oddziałów obrony przeciwlotniczej podczas rewii wojskowej na Polu Mokotowskim. Ciężki karabin maszynowy wz. 30 (wersja przeciwlotnicza) zamontowany na motocyklu Sokół 1000.
context_page_description: Ckm wz. 30 is a Polish-made clone of the American Browning M1917 heavy machine gun. Produced with various modifications such as greater caliber, longer barrel and adjustable sighting device, it was an improved although unlicensed copy of its predecessor, and was the standard machine gun of the Polish Army since 1931.
context_section_description: In mid-1930 the first test models were ready and were sent to various testing ranges. In March 1931 the first 200 models were sent to front-line units for further tests under the designation of Ckm wz.30. Serial production started by the end of that year. Among the most notable differences between the original and the Polish clone were:
  Different calibre, adapted to the Polish standard 7.92×57mm Mauser ammunition
  Loophole iron sights replaced with V-notch sights
  Butt handle of the weapon was lengthened for easier carriage
  Longer barrel for greater precision and accuracy
  Rifle lock was modified for easier exchange of used-up barrels
  The lock was modified for easier handling
  New mounting was adapted, with a mast for anti-aircraft fire
  Sights were adapted for anti-aircraft fire as well as a handle for aiming in the air was added
  Added flame suppressor
  Three types of a tripod mounting were developed and used in Poland. First was wz.30 mounting for infantry (weight 29.3 kg), superseded with improved wz.34 mounting (26.3 kg). Cavalry adopted more modern wz.36 mounting instead (17 kg). All tripods could be used for anti-aircraft fire, using a mast, transported in a rear leg in case of infantry mountings, or folded below the barrel and fulfilling also a role of a recoil shock absorber, in case of the cavalry mounting.
  Following the first tests, a series of additional modifications was introduced. In 1938 the trigger mechanism was replaced with a completely new, more reliable system. In addition, the lock was replaced for easier handling and keeping the weapon in good condition. The modified design received the designation of ckm wz.30a, though the name was rarely used by the soldiers themselves. The new version was also the basis of a ckm wz.30/39T design, designed for export to Turkey and adapted to Turkish standard 7.65×53mm Argentine ammunition. However, the design was never introduced in large numbers as the Turkish competition was halted after World War II broke out. In the late 30s, Wilniewczyc and Skrzypinski designed experimental barrels with a rifled oval barrel bore ("Lancaster rifling"). The barrels were very expensive to produce, but gave a significant increase of the accuracy and longevity of the barrel. Altogether, between 1931 and 1939, the Fabryka Karabinow ("Rifle Factory") in Warsaw built at least 8,401 ckm wz.30 for the Polish Army, in addition to 200 of information series (available are only data until March 1939, and several hundreds more were probably built by September 1939). In addition, quite a big number - over 1,700 - was exported by the SEPEWE syndicate to Republican Spain. There were trials to sell them also to other countries, like Romania, Bulgaria, Estonia, Yugoslavia and Argentina, but in spite of favourable participation in contests, the state factory had no resources to credit deliveries. Among others, in 1936 in Argentina the wz.30 machine gun was evaluated as more reliable and accurate than original Browning M1928, but Colt could ensure more favourable conditions of delivery. In 1938 Turkey ordered 500 wz.30/39T machine guns and probably at least part of this contract was fulfilled. Captured weapons were used by Nationalist Spain, Nazi Germany and Romania. After 1939, many preserved wz.30 machine guns were used by Polish partisan units (mainly Home Army), among others during Warsaw Uprising.
caption: Ckm wz. 30 mounted on a Polish Army motorcycle Sokół 1000 with the handle and sights adapted for anti-aircraft fire, photo from before 1 September 1939
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