I have one that feeds reliably in my M16. Works fine. Nice aspect of the design is the crank that is wound up to put tension on the spring. You can store it loaded with no tension until you use it. Since it is steel, should last indefinately as long as you don't let it rust. HTH.
Oh yeah, it is chinese, and I would not buy any more from china, either. However, they have been banned fom import, so china won't be getting any of the profit from those that are here now.