Thanks for sharing the information on MBX magazines. I didn't expect that it is 10 times more expensive.I shoot a AR9 in USPSA PCC competition--and 100% reliability is important. Currently using MBX magazines. NOT cheap!
Those plastic 30-round Glock style AR9 magazines are selling for about $15 a piece at gun shows. I'd be happy to pay a little more for some quality magazines. I wonder what's your favorite glock style AR9 magazines?