Add some firepower to your Sten gun with this 30 round magazine from masterpiece arms. This is a 30 round polymer gun magazine that fits 9mm sten guns. With older model guns a slight modification to the Mag may be required. Gunclip Depot has the largest selection of magazines and gun clips. If you do not see the gun magazine you are looking for send us an email and we will try to locate it for you. Orders shipped within 24 hours except week-ends and holidays.