magpul 30rd mag from academy $12 and a 4 finishing nails and some dremel time
http://i897.photobucket.com/albums/a...ps81c2e80e.jpg
http://i897.photobucket.com/albums/a...psdf818e4e.jpg
http://i897.photobucket.com/albums/a...ps62bc3047.jpg
http://i897.photobucket.com/albums/a...psb0bae299.jpg
http://i897.photobucket.com/albums/a...ps88334068.jpg
http://i897.photobucket.com/albums/a...psef1eab39.jpg
and here is a video of me cycling all 15 rounds out of it and yes it works every time
http://youtu.be/-TR97bvqCqM