For rust I like to use, Evapo-Rust used it on motorcycle parts and many others.
As far as i know it will not damage other material and its very safe. But make sure the part that needs to be cleaned stays submerged.
It's all about owners responsibility, keep them on a leash. I have two pitts, one of them a 7month old pup that also likes to play..yet his barking sounds very mean that scares strangers. Both of them I keep on a leash.
From a police point of view, better be safe than sorry. But I will be mad as well if that happens to me (about to submit my LTCH app) just moved from IL so i only have a FOID :(