The most full list of marks I found here (all in Russian, sorry):
http://guns.allzip.org/topic/36/1416490.html
It mainly repeats the list above posted by ljones, but there is some additional info.
Apparently, even in Russia there are no full list of the markings. The secrecy in the Soviet Union/Russia surrounding everything in the government is very paranoidal.
Especially if it's something which is totally innocent (like refurbished WWII weapons) and something which cannot be sold. For example, you can go on any Moscow market and find a CD with a copy of police database of all inhabitants in Moscow, for maybe 20 or 50 dollars. But at the same time, if you go to an industrial area in Russia and start taking photos of some stupid fences (and everything industrial in Russia is surrounded by ugly and usually crooked concrete fences), you will likely be arrested very quickly (but then probable will be released for a bribe, too).
When I was in the University, we studied some of electrical systems of Soviet military aircraft, nothing related to weapons etc., just support systems, navigation, etc. We had to stitch our notebooks together, number all pages in them, and they were checked by an officer and locked away in a safe in the end of each study day, so we could not take them home. The information in them was very basic and obviously known to "NATO spies" for a long time, but that were the rules.
So enthusiasts collect the info on markings bit by bit. Even though they participate in museum conferences dedicated to WWII firearms, etc, apparently, they do not have access to the military archives. Somewhere in the government/army there must be the list of all markings, but until somebody finds a way to buy this list somehow, the situation is unlikely to improve. Or could be just a haphazard decision of a government bureaucrat to release the list to an author writing a book on rifles, for example. One thing is certain about Russia, they are totally unpredictable from a normal logical point of view (they have their own logic, but it's very weird).
That's just my observations.