Hi Julian, thank you for your feedback on our BinTac T9 .357Cal 8 Rounds CNC Metal Magazine. We're glad to hear that you're enjoying the 357 round balls and Diablo that came with the T-9. We apologize for the inconvenience with the slugs not fitting in the mag. We'll make sure to look into this and see if there's a solution for you. Thank you for choosing our product and happy shooting!