Reczny Karabin Maszynowy wzor 28 (rkm wz.28)
The rkm wz.1928 was the standard LMG used by almost all Polish infantry and cavalry units during the German-Soviet Invasion of Poland in 1939. Based upon the Belgian R75 variant of the Colt M1918 Browning Automatic Rifle (BAR) designed by American John Moses Browning, the Polish government purchased 10,000 modified rifles from Fabrique Nationale d'Armes de Guerre of Herstal, Belgium in 1929; and negotiated to produce licensed copies in Poland.
Cavalry training with the rkm wz.28. Note kbk wz.98 rifles.
The Armaments Legacy confronting the Wojsko Polskie of the 2nd Republic:
"The Armistice that ended World War One saw the re-emergence of the Polish state after more than 100 years of domination by powers including Prussia, Russia, Germany, and Austria. The military charged with defending the nascent state found itself equipped with a collection of weapons that was eclectic to say the least. The light machine gun inventory was no exception to this situation. There were Lewis guns, Bergmann MG15na's, Madsens, Chauchats, and Maxims. It was decided that that a new light machine gun would be chosen by the army with which to replace all the disparate and obsolescent types." (Crufflers.com)
In July, 1924 a Polish Army Board was convened to organize a competition to choose a new light support weapon. The entrants included machine guns by Lewis, Madsen, Benèt-Merciè, the Hotchkiss Model 1922, and three versions of the Browning Automatic Rifle (BAR): the US M1918, the Fabrique Nationale Modèle 1922 (which was actually made by Colt), and the US M1922 Cavalry Machine Rifle. The initial competition concluded with no clear winner and the Board declined to accept any of the guns submitted. A second round of competition was scheduled for January and February, 1925. This next round featured more entrants, including the Madsen Model 24, the Beardmore-Farquhar Model 24, the French Lewis Model 23, the Chatellerault Model 24, the Hotchkiss Model 1922, the Italian ALA Model 24, a Swiss Furrer Model 25, and two commercial Colt 'inch pattern' Browning Automatic Rifles supplied to FN under earlier agreements between the two companies, one with a 500mm barrel and one with a 600mm barrel (Modèle 1924).
Overseen by the commandant of the Central Shooting School in Torun, Colonel Tadeusz Felsztyn, the field was narrowed to three entrants: the FN supplied Modèle 1924 BAR, the Hotchkiss Model 1922, and the French Lewis. The FN Modèle 1924 BAR was ultimately chosen, adoption dependent on eleven modifications to support the Polish Army's needs. Modifications included:
"The gun was to be chambered for the 7.92x57mm cartridge.
The bipod legs were to end in skids, not spikes.
The bipod was to be relocated from near the muzzle to the gas regulator.
The rear sight was to be turned 180 degrees so that the eye relief would be sufficient to replace the aperture with a U-notch.
The rate of fire reducer was to be eliminated.
The barrel was to be 611mm in length.
The operating rod was to be lengthened concomitant with the barrel.
The gas piston was to be redesigned and reinforced for added durability.
The gas regulator was to be accordingly redesigned.
The extractor and sear springs were to be redesigned.
The butt was to be redesigned to position the shooter's shoulder higher along the axis of the bore."
Early Polish rkm wz.28
Image credit: James Ballou, 'Rock in a Hard Place'.
Late Polish rkm wz.28
Image credit: James Ballou, 'Rock in a Hard Place'.
Receiver Markings: Fabrique Nationale production.
Receiver Markings: P.W.U.F.K. production, 1934.
rkm wz.28 schematic drawing (Karczewski).
rkm wz.28 field stripped.
Licensed production in Poland began in 1930 at the Panstwowa Fabryka Karabinow factory in Warsaw and approximately 10,660 rkm wz.28 were manufactured by 1939 with further modifications made to the iron sights and the addition of a fish tail butt stock. The Polish version was made with chrome-vanadium barrels with a life expectancy of 4000-5000 rounds, while the life expectancy for Belgian FN barrels was 3000-4000 rounds.
Purchase price for the rkm wz.28 was about 2060 zł. (additional set of spare parts: 1433 zł.)
The most serious shortcoming of the Polish rkm wz.28 was its lack of a quick change barrel (a feature that both Swedish m/37 and Dutch versions had) which, under extreme conditions, could result in overheating and subsequent burning out of the barrel. Planned modifications to improve accuracy for automatic fire included a folding buttplate like that found on the US M1918A2 BAR, a reinforced bipod with wider skids and stake holes, a muzzle compensator and to incorporate a quick change barrel. These modifications were introduced in the prototype wz.28/38B and the wz.28/38T, which underwent trials in December 1938. It was also intended to produce 852 training versions designed by J. Maroszek to use .22 caliber ammunition for the fiscal year 1940/41.
Type: Light Machine Gun
System of Operation: Gas
Caliber: 7.9x57mm Mauser
Capacity: 20 round box magazine
Rate of fire: 600 rds./min.
Practical rate of fire: 80 rds./min.
Muzzle Velocity: 815-850 m/sec.
Sights front: Blade,drift adjustable for windage
Sights, rear: Fully adjustable u-notch
Rear Sight Graduations: 300-1600m,
Length: 45.28" (1110mm)
Barrel: 24.05" (611mm)
Weight (unloaded): 20.5 lbs (9kg)
Effective Range: 800-1200m
Domestic Production by years:
1930 - 600 units
1931 - 2400 units
1932 - 860 units
1933 - 1355 units
1934 - 1550 units
1935 - 1500 units
1936 - 580 units
1937 - 650 units
1938 - 900 units
1939 - 315 units
TOTAL: 10,660 units
rkm wz.28, Nowa Deba training ground, 1938.
10th Cavalry Brigade motorcycle with sidecar and rkm wz.28.
A note on nomenclature:
"The Polish Army observed a distinction between types of light machine guns, and this distinction can be noted in the nomenclature assigned to the different models. Lekki karabin maszynowy or LKM, literally translates to light machine gun, and refers to a lightened version of a belt fed machine gun. A prime (but not Polish) example of this would be the Browning M1919A6. Alternatively, reczny karabin maszynowy or RKM, which translates to hand held machine gun, refers to magazine fed machine rifles or light machine guns such as the Bren or the BAR. This method of classification based on feed system was maintained until the beginning of World War Two." (Crufflers.com)
Anti Aircraft modifications to the rkm wz.28:
"In 1935, an improved variant of the wz.28 was introduced. Second variation wz.28's are all fitted with the distinctive anti-aircraft ring sight base on the barrel, possessed a large diameter front sight guard, a smaller battle-sight notch, a reshaped butt with a prominent "fish-tail" contour, a large flash hider, and a reinforced gas cylinder attachment. A special anti-aircraft conversion kit was issued with most wz.28's, consisting of the anti-aircraft ring sight, the anti-aircraft peep sight, and an oversize gas cylinder tube cross pin assembly which served as an axis for the anti-aircraft fork mount." (Crufflers.com)
rkm wz.28 with Anti Aircraft sights.
rkm wz.28 equipped with Anti Aircraft sights; Polish soldier and Auxiliary.
rkm wz.28 on wooden anti aircraft tripod (Polish museum exhibit).
A variation of the rkm wz.28 was the basis for development of an aerial, flexible machine gun, designated karabin maszynowy obserwatora wz.37 featuring improvements including a spade trigger, aerial sights, a higher firing rate, and a feeding mechanism module that would fit the wz.37 and allow feeding for sustained fire from a 91 round pan magazine. The wz.37 "Szczeniak" was used in PZL.37 Łoś bombers. (Leszek Erenfeicht)
Drawing of the km lot wz.37 by Leszek Erenfeicht.
Attempts were made to export the rkm wz.28 to other countries by the Polish export consortium 'SEPEWE'. One unit was sold to Greece and another to China in 1932. In 1936 E. Grimard of Paris sold 302 rkm wz.28's to Mexico, which were intended for the Spanish Republican government. Likewise in 1937, Gokkes-Wolff exported 225 rkm wz.28's, again to Mexico and also sold another 126 to Palestine along with spare parts. An additional 1100 rkm Wz.28's were sold to Greece by Gokkes-Wolff, which were again intended for Spain. The same year an estimated 40 units were exported to Palestine and Grimard purchased another 300 for export. Total export sales: 2,095 rkm wz.28.
During the Polish resistance to the Nazi and Soviet invasions, the rkm wz.28 was an effective weapon. After the fall of Poland, the rkm wz.28 was used by the Armia Krajowa (Home Army) and other partisan organizations that continued to resist the German invaders. After the defeat of Nazi Germany, the rkm wz.28 was used against the Soviet backed communist regime during the late 1940's civil war.
Warsaw Uprising: Barricade on intersection of Świętokrzyska and Mazowiecka Streets viewed from Napoleon Square from Epizody Powstania Warszawskiego, both photographs by Jerzy Tomaszewski.
Polish partisan - but whom is he fighting? (Narodowe Archiwum Cyfrowe)
Polish references for the rkm wz.28 include:
'RKM 7.92mm wz. Browning 1928' by A.Jońca and A.Zasieczny
'Small Arms and Artillery Equipment and WP Polish Forces in the years 1914-1939' by A.Kontankiewicz
'Polish Construction of Small Arms' by Z. Gwódźdź
'Border Protection Corps 1924 - 1939' by J.Prochowicz
'Polish Army Infantry 1918 - 1939' by Z.Jagiełło
English references for the Browning Automatic Rifle:
'Rock in a Hard Place: The Browning Automatic Rifle' by James L. Ballou
Polish web sites: Ręczny Karabin Maszynowy wz.1928 (Wielka Encyklopedia Uzbrojenia M.S.Wojsk. 1918 - 1939)
English web sites: Polish Air Force Guns and Ammunition 1918-1939. (POLISH AIR FORCE GUNS AND AMMUNITION 1918-1939)
Crufflers.com: 'Historic Firearm of the Month, December 2000: Wz.28: The Polish BAR' (Historic Firearm of the Month, December 2000)
Information and photos in this post was taken from Crufflers.com, Polish Air Force Guns and Ammunition 1918-1939, Wielka Encyklopedia Uzbrojenia M.S.Wojsk. 1918 - 1939 and various other Polish web sites using Google Translate. Apologies for not giving credit where due.
Last edited by dastier; 06-04-2012 at 04:04 AM. Reason: Added missing drawing of the km lot wz.37 and additional captions
Great addition to the thread all.
Found your info on the Polish BAR very interesting.
I wonder if theres any info about why the Madsen fell by the wayside in the trials .... ?
Enemy Use of the rkm wz.28.
If imitation is considered the sincerest form of flattery, then the use of the rkm wz.28 by Poland's enemies may be considered expediency...
Soviet troops and militia in defensive positions before Moscow. There is a famous Soviet newsreel showing Moscow citizens marching thru Red Square bearing captured rkm wz.28's.
German soldiers training and using the rkm wz.28 on the Eastern Front. The Heereswaffenamt Fremden Gerät (Wehrmacht Weaponry Office Captured Weapons List) designated captured rkm wz.28's with lMG28(p) and later lMG154(p).
The lMG154(p) had two variations, the lMG154/1(p) being the earlier version of the rkm wz.28 and the lMG154/2(p) being the later. The captured rkm wz.28's were issued to German combat formations for use as automatic rifles rather than as true light machine guns and were later replaced by Gewehr 41's and captured Soviet SVT38 and SVT40's.
Last edited by dastier; 06-07-2012 at 06:57 AM. Reason: Added additional info on German Army designations
Tajny km wz.37 - Oglnopolski miesicznik ODKRYWCA
To the best of my knowledge it is the second known copy. Both are in private collections.
P.S. Two years ago eight wz 28 machine guns went to the mill in UK because the dealer lost/or it expired Section 5 certificate. I' ve got pictures...sad sight.
RKM wz.28 magazine pouches, charger and spare parts kit:
Here are photographs of possible issue magazine pouches for the rkm wz.28. I believe each soldier armed with a rkm wz.28 carried 4 pouches which held three to five 20 round magazines for a total of 240 to 400 rounds on his person and 20 round magazine in the rifle.
His assistant carried a further 200 rounds in ten magazines. I believe this is consistent with what I was able to translate from Wielka Encyklopedia Uzbrojenia M.S.Wojsk. 1918 - 1939 but I would like someone to verify.
3 magazine capacity pouches, one with corner reinforcements, one without:
Later 5 magazine capacity pouch:
It was also mentioned that the soldiers would carry two tarpaulin bags(?) which I presume contained, more ammunition, the magazine charger, the AA gun sight and spare parts kit.
If anyone can help, that would be most appreciated as I do not read or speak Polish and am trying to make sense of what Google Translate offers up.
Last edited by dastier; 06-08-2012 at 05:44 AM.