This happened over the summer. While shooter was running handholds in his SCAR-20, the system jammed and couldn’t be cleared.
It had to be mortared to clear the live round in the chamber.
Ultimately we discovered that a loose primer had wedged itself into the mechanism. This caused the rifle to not fire since it was out of battery. Which immediately lead to the shooter trying to eject / load another round.
Which then caused a double feed.
“Shooting Guns & Having Fun”