Not sure if this has been mentioned at all, but if you've seen Enemy at the Gates or have a passing interest in Russian history during WW2, you'd know Zaytsev was their greatest sniper. On the Grimoire card for NLB it says "Rumors of this weapon's existence sent many a Guardian clawing through the corners of Old Russia, seeking its legend. Some believe its origins predate the Golden Age and served to liberate the old Earth nation from a terrible cycle of war." On Zaytsev's monument in Volgograd his most famous quote is etched, "For us there was no land beyond the Volga". Just a fun fact :)
I'm happy they put some good lore in the game finally. Wonder if there's more than that one too.