6.5×55mm Swedish, also known simply as , 6.5x55 SE, 6.5x55 Swede, or in its native military as (), meaning "6.5 mm cartridge model 94", referring to 1894, is a first-generation smokeless powder rimless bottlenecked rifle cartridge. The cartridge has most users in the Scandinavian countries, where it is known as the 6,5×55 or just "the 6,5".

It was introduced in the 1890s, and is still one of the most common cartridges in modern rifles built for the Scandinavian market today. The cartridge was developed in a joint Norwegian and Swedish effort starting in 1891 for use in the new service rifles then under consideration by the United Kingdoms of Sweden and Norway.Hanevik, Karl Egil (1998). Norske Militærgeværer etter 1867 In 1893, the cartridge was standardized and adopted under the name to facilitate logistical cooperation between Norway and Sweden. The two nations had independent armies and consequently the normal procedure at the time was for their respective governments to use the same ammunition and then purchase small arms of their choice. Norway adopted the Krag–Jørgensen M/1894 rifle, while Sweden adopted the Mauser m/1896 rifle design that was based on a Mauser service rifle designed around the 7×57mm Mauser cartridge.

The 6.5×55mm cartridge has a smaller bullet diameter and lower free recoil than other full-power service rifle cartridges like the .303 British, 7.92×57mm Mauser, .30-06 Springfield, and 7.62×54mmR. Thanks in part to its relatively roomy case which was designed for loading long, heavy bullets, and a diameter bolt face, it has proven more successful than other first-generation smokeless-powder military cartridges of similar bullet calibers, such as the 6×60mm US Navy, 6.5×54mm Mannlicher–Schönauer, 6.5×53mmR Dutch Mannlicher, 6.5×52mm Carcano and 6.5×50mm Arisaka.

While the original and colloquial cartridge name is 6.5×55mm, there are some variations in chamberings. In addition to the original 1890s specification, three modern chambering and ammunition pressure variations also exist. is the European C.I.P. designation with SE being the Swedish two-letter ISO country code.C.I.P. TDCC datasheet 6.5 x 55 SE is the American SAAMI designation (official SAAMI abbreviation 6.5×55).SAAMI Drawing 6.5x55 Swedish SAAMI – Z299.4 – Centerfire Rifle – 2015, PDF page 13 of 375 is the Scandinavian designation used by the Scandinavian shooting associations DFS, DGI and SvSF.Blaser løp med SE kammer - dfs.no

Other common but unofficial names for this cartridge include 6.5×55mm Swedish Mauser, and less commonly 6.5×55mm Mauser, 6.5×55mm Krag and 6.5×55mm Norwegian Krag.United States Defence Intelligence Agency - Small-Caliber Ammunition Identification Guide. Volume 1. Small-Arms Cartridges Up to 15 mm - RT Huntington - 1978 - apps.dtic.mil, Index No. 46, 6.5x55 page 30 and 56 (PDF page 37 and 62)United States Defence Intelligence Agency - Small-caliber ammunition identification guide (U) Volume 1 - Small-arms cartridges up to 15 mm (U) - published June 1978: Index No. 46, 6.5x55, page 30 and 56 (PDF page 47 and 83) The book Cartridge Cases refers to the cartridge as 6.5x55 Norway & Sweden.Cartridge Cases, Per Arne Andersen, Vidar Andersen, Trond Strømstad, 1st Edition 1995, page 136

History and development In 1886, France introduced a cartridge for use with the then-new smokeless propellant, introduced as Poudre B, in the 1886 pattern 8×50mmR Lebel, which started a military rifle ammunition revolution.

In 1891, the Swedish-Norwegian Rifle Commission started its work. After extensive ballistic tests where different calibers were tested (8 mm, 7.5 mm, 7 mm, 6.5 mm etc.), the optimal caliber was determined to be 6.5 mm (0.256 in). Following this decision, a joint Norwegian-Swedish commission was established in December 1893. This commission worked through a series of meetings to decide on the different measurements for the cartridge case. The Norwegians early presented a 6.5 mm rimless cartridge design, but the Swedes wanted a rimmed cartridge. As a compromise, the Norwegians produced an experimental semi-rimmed cartridge which was very similar to what would become the final version. The book Cartridge Cases refers to this cartridge as 6.5mm Norwegian Experimantal. This cartridge had a 6.7 mm bullet, a 55 mm long case, but differed from what became the final version by having a slightly less tapered shoulder, a slightly smaller diameter base (11.75 mm) as well as being semi-rimmed (12.6 mm). However, after a firearm demonstration by Mauser, the Swedes changed their mind and wanted a rimless design. After further discussions, a rimless cartridge case of 55 mm length was approved, and each possible measurement (diameter at base, diameter at neck, angle of case, angle of shoulder etc.) was decided upon. The corresponding dimensions of the cartridge chamber to be used in a future service rifle were also determined. At the time of its development the 6.5×55mm was a high-performance smokeless-powder cartridge. The design of the joint Norwegian-Swedish commission was subsequently adopted by the Norwegian and Swedish governments, and entered service in the Norwegian and Swedish militaries. The cartridge was also adopted by the Danish, Norwegian and Swedish civilian shooting associations DDS, DFS and FSR.

In 1984, the C.I.P. independently standardized the cartridge as , and revised their standard in 2002 and 2007.C.I.P. TDCC datasheet 6.5 x 55 SE

In 1990, a specification was introduced along with the Scandinavian target rifle by the Scandinavian shooting associations DDS, DFS and FSR with the designation which tightened up the original tolerances (minimum and maximum dimensions) of the 1893 design standard, added a slightly longer chamber space for the neck for increased safety with untrimmed reloads, and increased the pressure rating. The SKAN chambering is approved for firing any 6.5×55mm cartridges satisfying the aforementioned C.I.P. and SAAMI standards.

In 1993, the SAAMI also independently standardized the cartridge as 6.5×55mm Swedish, with the official SAAMI abbreviation being 6.5×55.

The closest European and American ballistic twins of the 6.5×55mm are probably the German 6.5×57mm Mauser and the American .260 Remington cartridges. While the 6.5×57mm and 6.5×55mm both require a long-action receiver, the shorter .260 Remington (being based on the .308 Winchester cartridge) can be fitted to a short bolt-action format. Other 21st century cartridges, like the 6.5×47mm Lapua and the 6.5mm Creedmoor that have entered the market also are able to provide similar performance to factory 6.5×55mm ammunition. However, the extra case volume of the 6.5×55mm promotes a longer lifespan of the cartridge case when reloading, and will provide higher velocities when handloaded to the same pressure as its more modern counterparts. However, the approved chamber pressure ratings for older rifles then may be exceeded.

Cartridge specifications Original specifications All Swedish Mauser bolt actions were proof tested with a single 6.5×55mm proof round developing approximately piezo pressure (55,000 CUP psi).de Haas, Frank, Bolt Action Rifles, Northfield, Illinois: DBI Books, Inc. (1984), , p. 31

The book Norske Militærgeværer etter 1867 cites each Norwegian military Krag–Jørgensen rifles in the beginning was fired at the factory (either Kongsberg Våpenfabrikk or Steyr) with proofing rounds rated at , and copper units of pressure. After a while, use of the proofing rounds was dropped, as they were viewed as "unnecessarily powerful". Proofing with and rounds was continued, as they were viewed as necessary to get the action threads "set" and thereby "strengthening the barrel". During this process, the chamber tended to lengthen by and a maximum of was accepted.Norske Militærgeværer etter 1867 (1998) by Karl Egil Hanevik, , page 137, 366 and 367

Swedish and Norwegian chamber differences rumor Some historians have assumed that there was a difference in cartridge blueprint measurements between Swedish and Norwegian 6.5×55mm ammunition, but this may be unintentional. Due to different interpretations of the blueprint standard, i.e. the standards of manufacturing using maximum chamber in the Krag vs. minimum chamber in the Swedish Mauser, a small percentage of the ammunition produced in Norway proved to be slightly oversize when chambered in the Swedish Mauser action, i.e. requiring a push on the bolt handle to chamber in the Swedish arm. A rumor arose not long after the 6.5×55mm cartridge was adopted that one could use Swedish ammunition in Norwegian rifles, but not Norwegian ammunition in Swedish rifles. Some even alleged that this incompatibility was deliberate, to give Norway the tactical advantage of using captured ammunition in a war, while denying the same advantage to Sweden. However, after the rumor first surfaced in 1900, the issue was examined by the Swedish military. They declared the difference to be insignificant, and that both the Swedish and Norwegian ammunition were within the specified parameters laid down. Despite this finding, the Swedish weapon-historian Josef Alm repeated the rumor in a book in the 1930s, leading many to believe that there was a significant difference between the ammunition manufactured in Norway and Sweden.

C.I.P. specifications The 6.5×55mm has 3.75 ml (57.9 gr H2O) cartridge case capacity. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt-action rifles and machine guns alike, under extreme conditions.

6.5×55mm maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).

Americans define the shoulder angle at alpha/2 ≈ 25.6 degrees. The common rifling twist rate for this cartridge is 220 mm (1 in 8.66 in), 4 grooves, Ø lands = , Ø grooves = , land width = , and the primer type is large rifle.

According to the official C.I.P. rulings the 6.5×55mm can handle up to Pmax piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This means that 6.5×55mm chambered arms in C.I.P. regulated countries are currently (2013) proof tested at PE piezo pressure.C.I.P. TDCC datasheet 6.5 x 55 SE

As Denmark, Norway, and Sweden are not C.I.P. member states, neither their civilian users nor their shooting associations DDS, DFS and FSR have to oblige to the C.I.P. rulings in force.

SAAMI specifications The SAAMI maximum average pressure (MAP) for this cartridge is piezo pressure measured with modern piezoelectric pressure gauges that more accurately measure chamber pressures or alternatively 46,000 CUP psi measured by the (outdated) deformation of a copper cylinder.ANSI/SAAMI Velocity & Pressure Data: Centerfire Rifle

SKAN specifications

The SKAN specification was introduced to tighten up the original tolerances of the 1893 design standard. Otherwise its measurements is almost identical to the original standard except for a slightly longer chamber space for the neck by less than a millimeter.Saksnummer 34/2018, Oppfølging av vedtak løp med SE kammer, Nordisk Formannsråd (Translation: National Rifle Association of Norway - Meeting protocol, case number 34/2018: Follow-up of on decisions regarding SE chamber, Nordic Chairman's Council) Complying barrels have usually been marked with "6,5 × 55 SKAN".

In 2018, the tighter C.I.P. chamber (6,5 × 55 SE) was banned from competitions in the Scandinavian shooting associations on the grounds of competitive equity and safety. Since 2020, regulation changes in Germany resulted in new SKAN barrels manufactured by SIG Sauer being marked "6,5 × 55 SE, approved for SKAN".Ny merking av SIG Sauer piper - dfs.no

The SKAN chambering is sometimes erroneously referred to as SCAN, however SKAN is the correct designation.

Military ammunition Nomenclature