The two most famous Socialists in the US right now are probably Bernie Sanders and Ocasio-Cortez. Both are very aggressively anti guns.
"The whole proletariat must be armed at once with muskets, rifles, cannon and ammunition, and the revival of the old-style citizens’ militia, directed against the workers, must be opposed. [...] Under no pretext should arms and ammunition be surrendered; any attempt to disarm the workers must be frustrated, by force if necessary." ~Karl Marx - Address of the Central Committee to the Communist League
Source: https://www.marxists.org/archive/marx/works/1847/communist-l...
That is not true of Bernie Sanders [0]. He has moved to some degree towards favoring more gun control laws than he used to, but he is by no means more anti-gun than most mainstream Democrats.
[0] https://www.npr.org/sections/itsallpolitics/2015/06/24/41718...
Actual hard left - the kind that actually believes in Marx and revolutions - is not a hive mind, but it is true that it tends to be a lot more acceptive of grassroots violence, and things that enable it (like guns). Which is not all that surprising, given the history of the movement.
Look up Redneck Revolt or Socialist Rifle Association to see what I'm talking about.