I've been looking around for a better bag for my M2 and M4 and this one was suggested by several different people. It seems a mite expensive for what it is; however, and it would be hard to justify that cost. I mean, a bag's a bag.
http://www.amazon.com/Artisan-Artist-AAACAM7100BLK-Oskars-One/dp/B000XZ4WR4
http://www.amazon.com/Artisan-Artist-AAACAM7100BLK-Oskars-One/dp/B000XZ4WR4