Board Thread:Off Topic/@comment-27425734-20170826213348/@comment-26397825-20170923102039

For magazine capacity, look at the actual size of the ammo rounds you want to use and work out how many should be in the magazine based of the length of the grip.

20 9mm rounds is about 20cm long. If that's too long for the grip, then it's too many bullets. Google the rim diameter of 9mm bullets and figure out how many would fit into the grip of your gun.