Firearms Blog visits the prop maker who made the Guns of the Caribbeans at ISS (Independent Studio Services). They actually made the pieces and then aged them.
https://www.thefirearmblog.com/blog/2020/07/05/guns-from-pirates-of-the-caribbean/
https://www.thefirearmblog.com/blog/2020/07/05/guns-from-pirates-of-the-caribbean/