Yeah, 1920's unfortunately but I've still set a recording for it. The Victorian period wouldn't have been as interesting, they were just as vicious but didn't have the guns, so threw rocks at each other or bashed peoples heads in with bricks. Guns look better on TV and the 20's were when they started to shift to organised crime etc, rather than being mobs* on the street.
*Those mobs could get damned deadly though, in the 1890's there was a period where multiple gangs were fighting for turf and there could be in the region of 500 Peaky Blinders (generic term for them, not the name of a gang, although I think that's what they've done in the TV show) on the streets having a maul. They didn't care about innocent bystanders either. Plenty of records of old women or kids etc getting caught in the crossfire and being hospitalised.