The Bushmaster ACR or Adaptive Combat Rifle features an adjustable gas piston system which runs cleaner and better than it's direct gas impingement counterparts. The ACR is a modular system which allows you to swap out barrels, stocks, and even hand guards. This particular version comes standard with a polymer hand guard and a folding/seven position telescoping stock. Additional it features a 18.5" cold hammer forged barrel along with ambidextrous controls that even a southpaw shooter would enjoy.