I use an Eagle Tac-V-NU vest, the one with mag pouches on the left side and horizontal pouches on the right side, been using it for MP 5 since 1996. Only changes have been to remove the mag flaps, 2-MP 5 30 rounders on a dual mag clamp fit perfect, I then have a Blade-Tech HK Mp 5 mag pouch for the emergency 15 rounder, and am getting at least one more Blade-Tech for 2 additional 30's.
I got a MP5 K shoulder rig from am94pm on these boards, sewed it into the vest, have 2 single 30's in it, total of 10-30's, 1-15, ( hence the HKPRO Indian name "he with too many magazines", come the MP 5 class in Indiana next year, you'll understand, LOL!).
I have also found that army surplus M-16 mag pouches, the older ones for alice rigs, will hold two 30's on a dual mag clamp, quite well, just have to get the flap out of the way. That gives me an idea!
Have to get some pics.