Unfortunately, there is not very much in print on these early experimental carbines designed by Sergey G. Simonov. Although an early prototype was completed in 1941, an order by the Artillery Committee to produce 50 prototypes for field testing was delayed until 1944. This was due to urgent wartime production of standard small arms designs.
As a result of the adoption of the M43 cartridge and the introduction of the folding bayonet to the Mosin Nagant carbine M44, the earlier prototype was modified accordingly, and field trials took place on the First Byelorussian Front in late 1944. Carbines were also sent to the Vistrel Officers Training School.
As a result of those trials, Simonov made several minor modifications, with production commencing in 1949. Several experimental versions were designed from 1950 to 1953, including a scoped, select fire, detachable bayonet and detachable magazine version. None were adopted.
I have not come across any published photos of Soviet soldiers using this carbine in 1944. The "Collector Grade" publication of this carbine has yet to been written. So, in depth study of it's development is sketchy at best.
Only "Soviet Small-Arms and Ammunition" by D. N. Bolotin (1995 Finnish Arms Museum Foundation) covered it superficially and provided a few photographs (from which the above pic is from).
It also contains 4 other photos of 1950's experimental SKS carbines.
