Watch this Video Thirty rounds and no recoil
The FN 5.7 has a 30 round magazine.
The FBI would not comment on what the agents were looking for at the mosque a full five days after the shooting, but motivation remains the focus.
"Obviously, the key is did he act alone," former senior FBI official Brad Garrett told ABC News. "And secondarily is, what evidence might potentially be in the dumpsters or at the mosque." LINK