The 8×63mm patron m/32 was a bottlenecked centrefire cartridge with a slightly () rebated rim for Swedish heavy and medium machine guns. It was used from 1932 to the finalisation of the re-chambering process of these machine guns to 7.62×51mm NATO in 1975.

History

Given the experiences of the devastating effect of small arms fire, including the long-range, even indirect fire of the machine guns, in the Russo-Japanese War and World War I, as well as a revolution in terminal ballistic calculations, calibre-related concerns occupied a lot of attention worldwide in military establishments. Sweden was no exception, and series of trials in calibres 6mm-12mm were conducted until the late 1920s. At this time, the standard service cartridge in Swedish use was the 6.5×55mm Swedish skarp patron m/94 projektil m/94 (live cartridge m/94 projectile m/94) service ammunition loaded with a long round-nosed m/94 (B-projectile) bullet. After study-travels by Lieutenant Colonel de Laval along with Captains Nygren and Holmgren, mainly to Germany and the Netherlands in October 1930, Royal Swedish Army Materiel Administration (Kungliga Armétygförvaltningen (KAF) appointed a commission that conducted a series of tests with calibres 6,5 mm to 7,2 – 7,5 – 7,9 mm, and bullet weights between 8.4 grams and 17.0 grams, with the intention to either recommend a new calibre for the kulspruta m14-29 or retain the 6.5×55mm but with a new boat tailed spitzer bullet, as the old blunt nosed projectile m/94 had inferior ballistics. The commission found that at ranges below , no recommendation could be given without indepth analysis of intended tasks within the tactical doctrine. Past this, the 14.2 gram bullet in calibre 7.9mm had superior performance in precision and penetration while not causing excessive barrel wear as well as fulfilling the requirement of 20 kilogram-metres impact force up to a range of . Based on this, KAF tasked AB Bofors to develop and manufacture the larger rifle cartridge to meet these needs.

Design The patron m/32 round had the same overall length as the .30-06 Springfield cartridge, which allowed it to fit in the standard Browning receiver, but used a larger diameter case and share the 6.5×55mm diameter bolt face. Compared to the 1928 pattern .30-06 Springfield M1 Ball the 8×63mm patron m/32 was loaded with S bore bullets and had more muzzle energy. The 8×63mm patron m/32 had a muzzle velocity of and an operating pressure of .

The patron m/32's aerodynamically refined boat tailed spitzer bullet had a useful range of approximately on which the impact energy was 20 kilogram-meters (196 J / 145 ft⋅lbf),The useful maximum range is defined by the maximum range of a small-arms projectile while still maintaining the minimum kinetic energy required to put unprotected personnel out of action, which is generally believed to be 15 kilogram-meters (147 J / 108 ft⋅lbf). and a maximum range of approximately when fired from a kulspruta m/36.Swedish Kulspruta m/36 at forgottenweapons.com Reverse engineering the trajectory from the previous sentence indicates a ballistic coefficient (G1 BC) of approximately 0.63. Available with armour piercing bullets, patron m/32 was used in the UN-forces' KP-bil during the Congo-crisis against the separatists' armoured cars.

The 8×63mm patron m/32 cartridge was used in the following machine guns:Arméplanch för utbildning fotograferad av Göta Vapenhistoriska Sällskap (in Swedish) Kulspruta m/14-29 Flygplanskulspruta m/22 Kulspruta m/36 Kulspruta m/39 Kulspruta m/42

The 8×63mm patron m/32 was also used in the gevär / pansarvärnsgevär m/40Sammanfattning av rapport Till Kungl. Arméförvaltningens artilleridepartement (in Swedish) bolt-action rifle, Karabiner 98k's re-chambered in Sweden for the patron m/32. Originally purchased as the pvg m/39 in 8×57 IS as a stop-gap anti-tank rifle (despite being unsuited for the role), the re-chambered 8×63 rifles were designated m/40, and later issued to machine gun crews so their rifles would fire the same round as their machine guns. Besides the rechambering a muzzle brake was added necessitated by the additional recoil produced by the more powerful 8×63mm patron m/32 cartridge.

Military ammunition

DesignationTypeWeights (gram)Propellant typeProjectile material(s)Muzzle velocity V0 or V25Burning rangeMarkingRemarksCartridgeProjectilePropellant8 mm sk ptr m/32FMJKspkr 1/0,55Lead core, Nickel jacket750 m/s (V25)NoneStandard Ball.8 mm sk ptr m/32 "For peacetime only"FMJ32,1714,23,6Kspkr 1/0,55Lead core, Nickel jacketBlue tipAmmunition of inferior quality. Used in peacetime.8 mm sk ptr m/32 "Not for machine guns"FMJ32,1714,23,6Kspkr 1/0,55Lead core, Nickel jacket760 m/sGreen tipSame as above but has green marking. This means "Not for machine guns"8 mm sk ptr m/32 pprj m/39AP29,711,83,6Kspkr 1/0,55 pbr3,2 g steel core780-810 m/sBlack tipOrdinary armor-piercing cartridge. Penetration of ~10 mm at 50 m8 mm sk ptr m/32 pprj m/40 or 8 mm pbr ptr m/32-40AP31,1415,73,6Kspkr 1/0,55 pbrTungsten core725 m/sTop half blackTungsten-cored ammunition. Penetration of ~20 mm at 0 m Only used in machine guns.8 mm sk ptr m/32 slprj m/39Tracer28,911,013,6Kspkr 1/0,55Projectile contains phosphorus, no boat tail780-824 m/sred 100-800 mRed tipFirst marking of slprj m/39White tipSecond marking of slprj m/39.8 mm sk ptr m/32 slprj m/39

"with a different primer"Tracer28,911,013,6Kspkr 1/0,55Projectile contains phosphorus, no boat tail780-824 m/sRed 100-800 mRed tipThe primer is dark gray and non-magnetic. Likely manufactured in Germany.8 mm sk ptr m/32 brandprj m/40Incendiary11,55Phosphorus and leadYellow tipIncendiary ammunition from Hungary. Trubbkula.8 mm sk ptr m/32 brandprj m/41Incendiary/AP27,79,8-9.93,6Kspkr 1/0,55 pbrHas an internal steel core surrounderd by fuel835-930 m/sOrange tipThe ammunition is primarily for aircraft and is a semi-armor piercing projectile8 mm Tysk B patron "Observation cartridge"High-explosive incendiaryBottom halve blackGerman B bullet loaded in a Swedish 8×63 cartridge. 8 mm sk blindptr m/32DummyNoneEarly marking.8 mm sk blindptr m/32DummyGreen tipLate marking.

The operating pressures of the various ammunition types varied between .

See also List of Swedish military calibres List of rebated rim cartridges 8 mm caliber

References

External links

8x63 M32 Bofors HISTORIC MACHINE GUN CARTRIDGES by Anthony G Williams 8x63 Swedish / 8x63 Bofors (in Russian) 8x63 Swedish Bofors / 8 mm Bofors / 8x63 Swedish For MG Mod.1932 / 8mm SK PTR M-32 / 8mm Sueco / 8x63 / SAA 4540 / XCR 08 063 BGC 010 (In Spanish) The Swedish military ammunition site Ammunitionsregister för armén, 1960 instruction drawings of 8×63mm patron m/32 ammunition Military Small Arms Ammunition of the World, 1945-1980, P. Labbett