+1 on these. They work great. I got this for my range bag. LA Police Gear Jumbo Bail Out Bag its pretty heavy-duty and has plenty of pouches for rifle and pistol mags too. There are some smaller ones one their site as well that may work if this one is too big.
I too have the midway bag very nice - as well I have "mag bag" for ammo and mags that I either carry separately or in the center section of the midway bag