I'd love to see that manual. The only time I've seen those procedures mentioned in Soviet literature is in Yur'yev's "Sport Shooting".If one consults the 1934 instructions for the "three-line rifle, model of 1891" and the 7.62mm rifle model 1891/30, there is a whole chapter on accurizing the M91 and M91/30 including the points of contact of the sear and the cocking knob/striker and the use of birch strips and metal shims and wrapped pieces of oiled felt to correctly bed Mosin-Nagant rifle stocks. Best believe with the kill ratios of Soviet snipers that these methods were applied to the PE and PU snipers.
As for "photos" of the procedures, I have no idea.
|1934 "How to Zero the 1891 and 1891/30 7.62mm Three Line Rifle" which appears in English translation as an appendix to Maj. (ret.) James F. Gebhardt and Paul Tamony, translators, _Soviet Sniper's Handbook, 1942_ (Leavenworth, KS: Russian Military Translations), 95-109.|