Bronze wool was made for using on boats rather than steel wool. Any remnants of the steel wool left on a boat hull would naturally rust, where remnants of bronze wool don't rust. Bronze wool is not any better than steel wool on removing rust on a pistol, and in fact the steel wool comes in finer grades. If bronze wool had been better, DWM would have used it bluing their pistols.
Up until the mid 1950's Remington Arms rust blued their shotguns and rifles. Instead of using steel wool they used power driven fine wire wheels which was faster than scrubbing the rust by hand. If the fine wire wheels didn't hurt the bluing, 4/0 steel wool sure won't hurt it.