This is the one that I bought and have my MP7 in. It fits like a GLOVE!
http://www.evike.com/Merchant2/merchant.mv...&Category_Code=
It's drop-leg on the right side, adjustable, and the thing on it that looks like it would hold shotgun shells is removable and has a velcro attachment, so you can replace it with any other standard velcro-backed mag holder.
Also, seeing as how the H&K Holsters & slings for the real steel MP7 are restricted to Law Enforcement & Military purchase by Purchase Order, this is definately one of the BEST holsters I could find.