Why not get them from eHobby?
http://shop.ehobbyasia.com/magazines...ark-earth.html
I can't quite remember. I believe you need to dremmel/file down the back of the mag where it enters the magwell, and/or you can file the rib on the back of the magwell in the gun itself. Just do a quick search with google and see what comes up. I know a few people who have done it and it doesn't seem too hard to do at all really.