Actually there was some pretty detailed discussion of the issue kit of devgru in Matt Bissonette's books. Specifically they each had two Heckler & Koch 416's, which were configured differently. One was a short (10"?) gun. He went into a lot of detail on the other individual kit they had as well.
I'm sure it's the same for the rest of JSOC (or as G3Kurz points out... already written) but at this point NSW does not, and never will again issue a direct impingement AR platform rifle.