GShG-7,62 / 9-A-662 / TKB-621 rotary gun

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aka "The Soviet Minigun"

Seems to be little original written about this rotary machine gun in the West, most of it repeats one or two sources.  So I spent some time trawling Russian-language web sites.


Development

• Development formally initiated by Council of Ministers Decree No. 1044-381 of 26 December 1968 ( the Soviets seemed to issue a lot of decrees on that day, just before the holiday season I suppose! ) .
  
• Decree called for parallel development of 7.62 and 12.7 mm weapons ( latter became YakB-12,7 ) to arm variants of the Mi-24 by providing a much higher rate of fire than existing single-barreled weapons
• The final 'G' in GshG indicates Eugene Glagolev who had joined the Tula works in 1966 and had made his name working on the GSh-23.  He was assigned as Chief Designer for the 7.62 rotary weapon. The 'GSh' is of course for senior Tula designers Gryazev and Shipunov.
• Tula manufacturing designation was ТКБ-621 and 9-A-662 assigned as armed forces designation in 1979.
• Number of barrels was set at four to reduce mass and spinning momentum for helicopter mounting.
• Problems in development included achieving reliable operation in icing conditions.

Specifications

• Often quoted as being "self-powered" but it is actually a combination of electrical motor to give the initial spin-up impulse and then gas-powered to maintain operation.
• Gas bled from firing each cartridge imparts a fore-aft momentum to a piston, which is converted to rotational movement by a cam arrangement.  This appears to be referred to in the Russian context as a "gas engine".
• Maximum sustained burst length is 1,000 rounds.
• Barrel life ( each ) is 40,000 rounds.

Personally I'm not sure what real advantage the hybrid form of operation gives; one still needs to carry a big, high-amp battery to spin-up the weapon.  I suppose the battery could have lower capacity than the equivalent for an M134 since it is not being continually drained. Edit: the third source listed below includes reference to reliability issues of the YakB-12,7 and mentions that the GShG's hybrid drive exhibited no such issues.  So now I'll have to investigate the larger weapon too...

Sources
http://rifles.3dn.ru/publ/gshg/1-1-0-5
http://en.valka.cz/viewtopic.php/t/10854
http://master-gun.com/velikie-oruzhejniki/evgenij-glagolev-%E2%80%93-sozdatel-pulemyota-gshg ( a biography of Glagolev, by far the best reference )

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Doing more research on these weapons might be a little easier now that I know their names in Cyrillic rather than transliterated!

ЯкБ-12,7
ГШГ-7,62

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\ Edit: the third source listed below includes reference to reliability issues of the YakB-12,7 and mentions that the GShG's hybrid drive exhibited no such issues.  So now I'll have to investigate the larger weapon too...

Seems that the YakB-12,7 was also gas-driven with a similar mechanism but initially suffered from lower than required RoF and was generally found to be fragile and unreliable.  Even the latest version has sustained bursts restricted to 750 rounds ( from 400 originally ) with barrel life increased 50% to 12,000 rounds.