I believe that it has to be pinned. For the fact it is marketed by Remington as using "standard M16/AR-15 Magazines"
It works on the same principal that a CX Storm mag has to be pinned to 5 but a 10 round M92 mag (or M96?--sorry, I'm not a Beretta guy) can be used, as long as it doesn't state "Storm" on it
Dang. I got to learn to type faster