Currently ATK has the contract for Lake City. DOD procurement relies on Lake City with "on the economy" resourcing as needed. Several years back the DOD purchased 6 million Israeli 5.56 rounds to meet training demands stateside while US production went to Iraq and Afghanistan.
The old days of ammo stockpiles are behind us now, the "Lean Logistic" model has taken hold, requiring military units to predict 6 months out their training expenditures (which is idiotic as training schedules aren't finalized until six weeks out). The "month to month" roll over accounting is gone too, the logisticians are trying to force clients to forecast and expend instead of putting ammo back into a supply point for use six weeks out on the next published training schedule.
Any Lake City brass on the market has either been fired, turned in to DOL and auctioned to the public, OR it was a production over run by the contractor running Lake City.
Machine guns are awesome until you have to carry one.