We got the DefendAR model. First time I shot it at the Illinois farm, wind was south at 20mph, sheriff pulled in. "Had a report of machine gun fire" Showed him the gun: "Ah those are perfectly legal, carry on"
Apparently a neighbor two mile north called it in.
We added a vertical fore grip to help control and push forward to file, and swapped the trigger for a RR two stage.
Make sure your finger is off the trigger area completely until it's shouldered and aimed properly and have the safety on! Load 2-3 rounds and practice. We've had two different issues with noobs. First one shouldered it with finger by trigger and it fired. The other incident was taking it off the shoulder (with finger on trigger rest) and it racked off two rounds into the dirt 5 feet in front of the shooter.
Fun as hell, but somebody is going to get maimed or worse I suspect.