I got the open top pouch with the bungee.
The main issue is that the actual nylon for the pouch is too high up, as in it swallows all of maybe 1/2 inch of the magazine. This makes for getting it out a total bitch.
To complicate matters, the bungee doesn't do shit because of the poor design. Since the magazine sits so low in the pouch, the bungee sits another 1/2 inch above it, doing....nothing. It basically just impedes you from grabbing the mag because you now have the bungee sitting directly above the middle of the mag but since the mag is so long the bungee is too short to clear towards either end of it, yet it doesn't actually positively hold the mag into place because there isn't enough of the mag sticking out to actually engage the bungee.
If you cinch the excess shock cord to make the bungee touch the mag, its impossible to pull the actual mag out.
It's fucking retarded.
I'm looking at something TYR makes for the Barrett 338 as well as for the PSR.
http://www.tyrtactical.com/products/details/magazine-rifle/10-round-single-338-barett-mag-pouch/
http://www.tyrtactical.com/products/details/magazine-rifle-sr/10-round-338-mag-pouch/