Here is an interesting concept in magazine pouches. The PFC PriMAC Magazine Pouch from Specter Gear holds the magazine at an angle which makes good sense ergonomically.
The PFC PriMAC Magazine Pouch came about via a collaboration between Specter Gear and Progressive Force Concepts. It is an open top magazine pouch that looks to have very good retention while still offering very quick magazine removal. The angle allows it to fall under the hand more naturally than a traditional vertical magazine pouch.
All of these features allow the PFC PriMAC Magazine Pouch to serve as a “speed reload pouch” for those who like to designate a pouch as there primary reload source. Essentially, the PFC PriMAC Magazine Pouch would feed the rifle while the other pouches feed the PFC PriMAC Magazine Pouch.
One potential downside is that the pouch is specific to either left or right handed shooters (it is available in two versions – one for left handed users, one for right handed users). It is not technically ambidextrous like a traditional vertical pouch would be. Though I suspect that with some practice, this could be mitigated.
Check out the PFC PriMAC Magazine Pouch on SpecterGear.com.