It is a fact that the Stalin regime did not perpetrate its crimes against the Soviet people until after convincing them to surrender their arms.  Before that nearly every Soviet village had its own cache of firearms and ammunition.  I suspect there were more than a few old Bolshevik veterans who would have quickly begun handing out those firearms once Stalin's treachery became known--had the weapons been there to distribute.

I have little information on the significance of this with respect to Hitler, except that gun clubs in Austria held off the Nazi invasion there for several days, but were ultimately outnumbered and outgunned.

I know even less about the role firearm access played (or didn't play) in China or Cambodia.  Perhaps you'll elaborate on this.