For a company with no lobbyist the past decade, Colt has done pretty well. First, they manage to convince a federal court that the M4 is a new weapon compared to the M16 and that they have exclusive rights to the TDP.
Then after losing M16 production to FNMI, they manage to convince the Army to buy M4s as a replacement. Normally a new rifle would require an open competition; but now Colt argues the M4 is just a derivative of the M16 and so no open competition is necessary.
Then to put the cherry on top, the XM8 program is successfully killed off when it tries to pull the same trick as opponents argue that the XM8 is sufficiently different from the XM29 that won the open competition to require a new open competition. Instead of a new competition, the program gets the axe entirely. Interesting that H&K submitted the XM8 for the dust trials and did well; but is submitting the HK416 for the M4 Replacement Trials. In fact, given all the development on the XM8, it is strange you don't see it anywhere. Bet there is a good story behind that...