#korobov

That’s a good question the TKB-022PM is on of Korobov’s designs which placed the magazine to the very rear of the weapon.  Most bullpup designs today like the LA85, Tavor, FAMAS and the Steyr AUG place the magazine with the rifle’s bolt and chamber - normally about 3/4 along the rifle’s full length.   

The TKB-022PM instead uses as vertical bolt, unlike the AK and AR the gas system surrounds the around the barrel in a sort of loop this moves the bolt backwards once fired, ejects the round, moves the bolt (literally) up and down and a u-shaped ‘rammer’ brings the next round forward from the magazine.  This unusual configuration allows the rifle to minimize its length and have the magazine positioned all the way to the rear.

I hope that explains it, I’ve never had the chance to look inside one so I’ve only been able to explain it as clearly as I can from what I’ve read.  Thanks for the question!

Korobov, the Bullpup Rifle and the TKB-022

By the early 1960s the AK47 and subsequently the AKM had been in Soviet service for nearly 15 years.  Approximately 10 million rifles had been made and the designs had been shared with half a dozen allies including China, the East German Republic, Hungary and Egypt.  

However, during the early 1960s Soviet small arms konstruktors were at work on another rifle which was quite unlike the AK.  The team of konstructors was lead by German A. Korobov (see image one) a designer who had also entered the same contest Mikhail Kalashnikov entered and won with his Avtomat Kalashnikova in the mid-late 1940s.  Korobov, a designer at the Tula arms plant, entered the competition with one of the world's first practical bullpup assault rifle designs, the TKB-408 (see image two), the design lost out to Kalashnikov's and while Korobov was disenchanted with the bullpup configuration he did not fully abandon the concept.

With the development of a new phase of mobile warfare in the 1960s which saw troops travelling less on foot and more onboard helicopters and inside armoured personnel carriers the Red Army decided to look into the development of a shorter rifle. Korobov and his team again entered the state sponsored competition. In 1962 Korobov designed the TKB-022, another bullpup (see image three).  The TKB prefix is an initialism for 'Tulskoe Konstructorskoe Buro' which translates as the 'Tula Design Bureau'. The TKB-022 looked unlike any other contemporary military rifle, its trigger group was located beneath the rifle's barrel and just in front of an integrated magazine/pistol grip - a configuration similar to the Uzi's. It also featured another advanced design feature, a moulded plastic stock which fitted around the receiver.

While Korobov's initial design was rejected he continued developing and between 1962 and 1968 he built several more variants of the TKB-022. The first was the TKB-022P No. 2 (see image four) which featured a standard AK trigger and pistol grip with the magazine no longer integral and set back further along the stock.  The TKB-022PM No.1 (see image five) saw the weapon's configuration alter significantly with the magazine and chamber being moved to the rear of the rifle while the trigger group moved to the front of the weapon (a stock shape not unlike FN's recent P-90 and F-2000). The last variant, the TKB-022PM5 No.1 (see image six) had a more evolved and ergonomic plastic stock and was chambered in the new Soviet 5.6x39mm experimental cartridge.  

The TKB had an overall length of just over 20 inches, significantly shorter than the AKM's 32 inch length.  With the unusual positioning of the rifle's trigger and magazine it had an unconventional vertically moving bolt - rather than the standard horizontal orientation.  This also meant that the bolt could not extract a spent round and instead Korobov designed a U-shaped extractor which pulled with empty casing from the chamber and then pushed forward the next round.

The TKB-022 was never adopted by the Soviet Union, possibly because of the rifle's unconventional configuration (which would not see widespread adoption until the 1980s), possibly because of the untested nature of the plastic stocks it is likely that there were concerns regarding its hardiness in extreme temperatures. It is also possible the TKB's unconventional bolt raised concerns among senior Soviet konstruktors. Regardless of the reason the TKB-022 in all its configurations and variants was undoubtedly a rifle well ahead of its time.  

Sources:

Image One Source

Image Two Source

Image Three - Six Source