I just picked up a new DDM4V7 yesterday, noticed the rail rotated, then noticed that the barrel wobbled. I removed the MRF rail and found the barrel nut wasn't even fully hand tight.
The rifle was inspected by CR on 4-10 according to the tag (you should give them crap because they initialed the date line, and dated the initial line on the tag...attention to detail!).
The website shows the barrel nut wrench out of stock. Do you guys have a commonly available work-around wrench you could recommend?