There's a scene in the movie Bernie where a man talks about a district attorney:
One thing Danny Buck's good at is getting Danny Buck re-elected. And he gets his little photo ops in the paper, busting up the copper rings or the hub-cap rings, or the meth labs, but in slow times, Danny Buck be out digging up some shit.
I think "ring" here obviously means "gang," but what are "copper rings" and "hub-cap rings"? There is no previous mention in the movie, and these seem out of the blue.
Yes, ring roughly means gang.
ring
a group of people who help each other, often secretly and in a way that is to their advantage:
a drug ring
a spy ring
(Cambridge Dictionary)
A copper ring, or a hubcap ring, is a group or network of thieves who steal copper, or hubcaps. Copper and hubcaps are easy targets for theft. The movie didn't mention these rings previously because these thefts have been wide-spread in real life, even in recent times (for example, Copper theft 'like an epidemic' sweeping US). Naturally, it's a concern for voters and they like to see the candidate doing something about it.
Some very petty criminal gangs steal hub caps, or copper. So it’s a gang of copper thieves or a gang of hub cap thieves.
