The military has been looking to update and replace their old workhorse M4 for a while and compation has been going on for Firearms manufactors to win a contract to do just that. The Bushmaster ACR is just one such example. Originally designed by Magpul as the Masada Bushmaster took over production of the rifle and dropped the Masada name.
Designed to incorporate several good qualities of today's battle rifles into one weapon system the ACR is chambered in the 5.56 Nato round and can be easily configured for each individual shooter. The gas piston firing system allows the weapon to function reliably under many conditions that the M4 can just not handle including over the beach drills and being caked in mud and sand. The civilian version should be out but with today's prices it's going to be a humdinger of price point even if the MSRP is sub $2k the dealer mark up is going to be crazy.
Check out this video of the Bushmaster ACR in action on the range
