As the title says I got it as an open box item, looked brand new put of the box only thing missing was the mag base plate hence the extended one on there now. The pin at the back is held in place by a 1/16 allen screw. Speaking on the mag it has no leaks and runs just fine. The gun has been fielded once for a functionality test and it runs as you'd expect. Can provide shooting video on request. Contact for more details.