Not a subscriber, never owned the mag but one of my readers made me aware of this in RECOIL Issue #4:

‎"...the MP71A is unavailable to civilians and for good measure. We all know that's technology no civvies should ever get to lay their hands on. This is a purpose-built weapon with no sporting applications to speak of."

Jim Zumbo anyone?

Here's a link to the original post blowing up on their Facebook page. Even if you don't have a FB account you should be able to read it:

https://www.facebook.com/Recoil.gun....60458947366646