I have this 20mm Armor Piercing with the following dimensions; OAL 57.4mm (2.26"), base to rotating band 13.21mm (.52"), RB width 5.33mm (.21"). Diameter of AP is 13.03mm (.513"). I'm hesitant to hope what this is, but could someone give me some ideas on what I might have. AP core isn't fazed by a file. The aluminum body is corroded having no visible markings. Thanks, Bruce.



