British Surplus Osprey Single Mag MOLLE Pouch

Open top mag pouches: not the most secure.  But they are pretty fast (!) and give you options for what you want to stow in said pouch. 

So mayyyyybe don't have ALL open top pouches, but having 1-2 of these where you can maintain control of the items (front or side) would be a not bad idea for things you need rapid access to, like an emergency reload.  

The Brits had their nylon pouches made by Osprey, the California outdoor backpack company.  That's pretty neat.