I keep encountering people who repeat the claim that the USSR was never really communist and from my, albeit very limited, understanding of history that seems rather inaccurate. So naturally I'm curious to see what historians who have dug into the facts of the matter have to say on it.
I would guess it's more complicated with stuff like "Well, during this the timeframe X they were very in line with communist thinker Y but really there is a lot of diversity" so I would be very thankful for being pointed to any sources which talk about it at length.
EDIT: Just to clarify, I'm asking of how in line the politics of the USSR were in regards to "communist"-ideology, specifically I would assume Marxist, not whether they were at the economic stage as described by Marx.
This question is not inherently historical, rather political. Without futher defining what we mean with communism, it would not be possible to answer from a historical viewpoint.
Ultimately, this is a question of semantics, not necessarily history. When it comes to words as abstract as "Communism", a lot can be up to the interpretation. A prevalent definition of "Communism" held by Marxist-Leninists, among most other communist groups, historically would describe a communist society as stateless and classless, and as such, as far as I know, none of the prominent founder of the Soviet Union would have considered the Soviet Union to be "communist" in the first place. I recall reading somewhere about a Russian slogan saying something along the lines of "Our children will live in communism", if that helps it make more sense, as for the most part, a communist society was seen as a goal.
So, as for the Marxist definition of "Communism", the Soviet Union is a pretty clear "No". Again, though, semantics is hard.
In reality, the soviet Union themselves never claimed to be communist. They only claimed to be working towards^tm communism. Here's an old Yerevan radio joke:
Q: We are told that the communism is already seen at the horizon. What then is a horizon?
A: Horizon is an imaginary line which moves away each time you approach it.
Communism was a goal for the USSR, not a reality. A good quick check to see if a nation was communist is by looking at their currency-- if it exists, the nation isn't communist/socialist in the original sense. It could be reduced to a matter of semantics though.