@buffalowinter - any chance you ever came across any of these? Appears to be some interesting stuff! The Soviets used Mosin actions as well as Ross 1910's and others I dont recognize..
See here:
http://www.thefirearmblog.com/blog/2016/01/10/5-45x39-small-but-perfect-a-history-of-development/
http://forums.gunboards.com/showthread.php?771354-Vostok-biathlon-rifle-in-6-5x54R
http://www.mosin-nagant.de/konfuze_schiebt.html
See here:
http://www.thefirearmblog.com/blog/2016/01/10/5-45x39-small-but-perfect-a-history-of-development/
http://forums.gunboards.com/showthread.php?771354-Vostok-biathlon-rifle-in-6-5x54R
http://www.mosin-nagant.de/konfuze_schiebt.html