Here are my notes on the 8.2x66R (or SR) :
Russia produced two sporting calibres based on a unique semi-rimmed (non military) case design with a 13.15mm base, 12.35mm groove and 14.3mm rim. This case appears originally to have been derived from a combination of the 7.62x54R Mosin-Nagant case (SV14) and the 10.66x57R Russian Berdan. It uses the same rim dimension as the 7.62x54R and the base of the 7.62x54R is the same as the groove on the 8.2x66R. However, the base on these “KO” types has been enlarged to 13.15mm which is the same as the 10.66x57R Russian Berdan cartridge. This would allow Mosin-Nagant Rifles to be re-chambered for this larger diameter case and obviously allow a greater powder charge for a given case length producing higher performance.
The 8.2x66R is the earlier and commoner of the two KO calibres (see also the 9x64 SV10) and was intended for use in the bolt action KO-8.2 Hunting Carbine (which was a converted military rifle). Note : K = Karabin (Carbine) and O = Ochotnicij (‘Hunting’). No hs are known on this cartridge cases. Plain lead, SN and FMJ bullets are all known loaded in this case but not all may be original.
There is mixed information about when this was introduced and also whether it is still used:
Badalik believed that this was introduced in 1953, others 1950’s but some evidence states that it may have been as early as 1946.
There is also conjecture thay this may have been the calibre for the HK-8.2 Rifle developed in the 1930’s by D.M. Kocetov. According to DocAv : “The initial 1930s development was for a Sniping rifle, and the action is a modified Mosin Action; by 1948, the Sniping part was dropped, and it became a “Government Issue Hunter’s Rifle” for use in outer Siberia for large game (Bear and Elk and Sheep) hunting.” However DocAv has also previously stated : “They were initially developed in the late 1930s as a dedicated hunting cartridge for Government-licensed meat and skin hunters in Siberia.”
According to a Russian website (translated) : Hunting carbine NK -8,2 under the cartridge of 8,2kh’’ mm : NK -8,2 - hunting carbine of the caliber of 8,2 mm the construction of D.M.Kochetova on the base of
mm rifle S.L.Mosina under the cartridge of 8,2kh’’ mm with the special case, which has cap without the flange and housing of the increased capacity. Was made in series at the Tula arms factory in 1931-1941 the planned long-range cartridge of large power so not it was released. Were sold only cartridges with the uncoated lead bullet." [ED : This could be another case type <> 8.2x53R SV3 ??.]
In 1962 a more powerful version was introduced known as the “8.2x66M” (where ‘M’ stands for ‘modernised’). Production of weapons using this cartridge ceased in 1976 as the 308 Winchester was introduced into the USSR for hunting.
Here are my notes on the 9x64R (or SR):
Russia produced two sporting calibres based on a unique semi-rimmed (non military) case design with a 13.15mm base, 12.35mm groove and 14.3mm rim. This case appears originally to have been derived from the 7.62x54R Mosin-Nagant case (SV14) using the same rim dimension and the base of the 7.62x54R is the same as the groove on the KO. The base on the KO types has however been enlarged to 13.15mm. This would allow Mosin-Nagant Rifles to be re-chambered for this larger diameter case and obviously allow a greater powder charge for a given case length producing higher performance. No hs are known on this cartridge cases and the manufacturer and years of introduction are not known for certain but believed to have commenced in the 1946/47 period.
Note : K = Karabin (Carbine) and O = Ochotnicij (‘Hunting’)
The 9x64R is is the most powerful of the Russian sporting calibres and is believed to have been developed by the Russian gun designer M.N. Bljum. It was developed later (c1955-57) but using the same case type as the 8.2x66R (SV10). Used in the bolt action K0-9 and “B-9” Hunting Carbines. Only loaded with SN bullets and this calibre is practically unknown outside of Russia.