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 would 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. As Denmark, Norway and Sweden are no C.I.P. member states, 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pressure gauges that more accurately measure chamber pressures or alternatively 46,000 CUP psi measured by the (outdated) deformation of a copper cylinder. 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. 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, regulations changes in Germany resulted in new SKAN barrels manufactured by SIG Sauer being be marked "6,5 × 55 SE, approved for SKAN". The SKAN chambering is sometimes erroneously referred to as SCAN, however SKAN is the correct designation. Military ammunition Nomenclature In the militaries of Sweden and Norway the 6.5×55mm cartridge