I had that done to mine. I just took it to my local gunsmith. He modified the 10 round box magazine which can now be used as a removable magazine. I have a 5 rounder for it, and he is working on a high cap mag for me for it. As far as removable magazines that you can buy at gun shows for it, you have to be carefull, because alot of them have problems with fitting, and function/reliability.