Machine gun was a precious weapon at the beginning of the SCW especially for militias fighting against rebel soldiers. In Barcelona just before first shots were fired some firearms were gathered thanks to CNT-FAI sympathisers in army ranks. More were captured after taking army barracks and defeating rebel troops that tried to take the city.
Spanish army was using various MGs mostly obsolete such as Hotchkiss 1909 French MG used in the I World War . It's the main weapon of the militia MG section I've painted.
It's worth noticing that there's a woman among fighters. In 1936 they served in militias on equal terms with men including in frontline units. Later when stalinists gained more power and dissolved militias they had to return to support units.