Well, what can I say other than poor weapons maintenance!!!
I was all over the world with my M16A2/M4 and as long as I cleaned it, it never let me down!!!! unless we were using blanks, those rounds REALLY gunk up a rifle fast!
Also, my personal observations of support troops weapons was that they didn't use them much so why clean them?! Not all were this way but most were including the crew served weapons!!
Not to mention the fact that the guy closest to the camera has an AD when he clearly pulls the trigger with the rifle pointed two feet in front of him... These guys don't look like they've had much range time with rifles before.
doesn't look like they knew the proper way to deal with a malfunction either... I don't think he inspected the chamber or dropped the mag once... just kept charging the weapon and pulling the trigger