Paces,
but Meters will do.....
seriously if you mean the full size M91/30 rifle (and the carbines may fall under this as well). the unit of measure used to graduate the sights is a "Pace" (can't remember the word in Russian right now been too long since i read the articles and books that mentioned this).
this i THINK would up being something like "a meter plus a little" but it WAS a standard set ubn stone measurement, for the Russian army and thus if you know what the marks equal you can aproxiamte where to put them for known, "modern standard" distances.
for this rifle things like "what unit of measure to mark the sights in" were decided during a time when most russians had little concept of what a "meter","yard", or "foot" was, at least not in the way we do now.