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.
Because a relatively small amount of the population can fight a successful guerrilla war, especially if they were to show success of some form(taking a region or something) declaring the socialist state invalid and thus receiving support from NATO and such.
In a world without a global order set against you to create unrest and conflict in your society yes, the citizens should be freely armed.