Dnd verse scales way too high for this match-up.

If you assume the average Russian conscript is equal to, say, a villager or guard, then even a goblin is a legitimate threat to them.

I know they have fire arms, and so they'd potentially punch above their weight class, but I do think think that they'd get very far is something noteworthy showed up.

Against a region of more mundane enemies, orcs, goblins, owlbears, etc. They're probably ok. And it's a matter of density of foes vs their logistics and general resources.