Acid peroxide will dissolve copper but is slow, heat helps but uses more acid and oxygen in gas fumes, depending on how much heat.
If you do not mind time factor, and amount of waste generated, it works good.
stirring well also helps.
If pins are heavy plated in gold I would nip off tip of top with cutters, so acid can also attack copper from that end I have found that it is hard for HCl acid and peroxide to go into a tube to attack copper, with a closed end when air bubbles are trying to come out of tube, thin plated pins do not worry about cutting tip.
