As far as I know, all of them - USSR, Cuba, China, Vietnam, NK etc, implement gun control. Why should their governments do that? The people of these states genuinely support(ed) socialism, if they are/were all armed they can protect socialism far better than the 1% of the population that makes up the military.
They implemented gun control for all citizens
So control but not an outright ban, right?
Just spitballing...
So there were lots of people who just didn't want guns, maybe?
Worried about the flow of guns into black markets, maybe?
Leadership not completely trusting the workers, maybe?
Keeping military style weapons limited to military and organized militia and leaving other small arms (pistols, non-automatic long rifles) for people who hunted or something?