Based on the standard military 7.62×39 Russian M43 case lengthened to 45.5 mm in an endeavour to increase the velocity.  The cartridge has been in existence since 1967 and was designed as a match target cartridge for use by the USSR biathlon team.  It remained in use until the mid 1970’s when the 5.56mm rimfire cartridge was standardised by the International Biathlon Union.  It was used by the Soviet team in the Norwegian biathlon championships in 1977. The cartridge exists with military style headstamps with factory codes 539 of Tula Armoury (on 1967 and 1968 date codes) and in the unheadstamped form which was obtained from Soviet military boxes dated 1975. It is rumoured that Zavod v Podolsku in Klimovsk produced cases with the 711 factory code but this remains unsubstantiated.