So I was at Creative Outdoors today. Apprently they got a whole bunch of U.S. Nam issue pouches, the ones that have a snap button and fits M16 VN mags perfectly are apprerently Compass pouches but it works well when you take the metal clip off and put a velcro strap through it and atatch through the two holes that you find in an M4 stock. If you can find the pouch and you feel that you could use the extra 20 rounds or just for looks this is a cheap 3 dollar idea!
Creativeonline.ca is their site but its only worth checking out if you're in Toronto/Markham area, its not really worth the gas hahaha
I'll post pics next week my camera is dead....
http://www.airsoftcanada.com/gallery....php?i=2937&c=
Its similar to the very top pouch on the right! Sorry if i borrowed ur pic but I can't find a better one hope you don't mind!!