Solid mag. Well built. All metal case so can take the abuse of field play as well as indoor. Haven't come across an M4 gun yet that has feed problems. Sometimes the key has slight difficulty to get into the winder and you need to do something to make sure you don't lose the key. Can easily be misplaced in you gear or work it's way down to the bottom of a pouch.
easy to load, wind and go much faster than typical high cap
getting the key in the winder hole sometimes
key can get lost easily if not firmly attached to person or pouch
Rating: [4 of 5 Stars!]