LWRC's IC-A5 Upper Receiver is a perfect start to a custom, high-performance AR-build. Originally designed for the U. S. Army's Individual Carbine program the IC-A5 Upper is equipped with a patented short-stroke gas piston system offering the shooter unparalleled reliability and easy maintenance in any conditions. The short-stroke gas piston system is perfectly paired with a nickel-boron coated bolt carrier for unmatched resistance to wear and corrosion while also providing permanent lubricity. This IC-A5 Upper Receiver is a Monoforge design with integrated 9" SPR style rail base (11" SPR style rail base for 12.7" barrel versions) and a low profile 2 position adjustable gas block allowing the shooter to compensate for running a suppressor with the added benefit of a longer modular rail system. The upper rail section on the IC-A5 Upper Receiver is an aesthetically pleasing special cutback version which allows the use of a low profile gas block and at the same time keep the full 9" modular rails available on the sides and bottom of the hand guards. Features of the IC-A5 Upper Receiver: LWRCI PROPRIETARY SHORT STROKE GAS PISTON SYSTEMLWRCI COLD HAMMER FORGED SPIRAL FLUTED NICORR-TREATED BARREL (10.5" barrels are non-fluted)LWRCI ADJUSTABLE 2 POSITION GAS BLOCKLWRCI BIRDCAGE (A2) FLASH HIDERLWRCI SKIRMISH BACK UP IRON SIGHTSLWRCI 9" USER CONFIGURABLE RAIL SYSTEM (11" RAIL ON 12.7" MODELS)LWRCI AMBIDEXTROUS CHARGING HANDLEH2 BUFFERCARBINE LENGTH ACTION SPRING LWRC International LWRC IC-A5 5.56mm NATO 10.5" 1:7" 1/2x28 OD Green Complete Upper Receiver ICA5U5ODG10S