Nylon bristles are a nice alternative. - Tipton 14 Piece Rifle Bore Brush Set

When checking for copper in a barrel, it is nice to have a tool that does not contain copper, and removes the chance of a false positive.
Pros: Will not give false positive copper indication.
Cons: May not last as long as bronze.

This review was written in the old system and had content requirements that are different than reviews written today.