Upper Half, M4 Carbine, A3, 16" - PISTON

AR15 / M16 A3 Upper half with 16" M4 contour barrel and A3 Upper receiver. Item # AR-UHM4A3Piston. This 5.56mm cal barrel is 16" long, threaded the standard 1/2 x 28 tpi, and has an A2 flash hider with the correct crush washer. It sports M4 contour and length handguards with full heat shields, and a correctly sized gas port for reliable function in full or semi auto. This upper has a complete short stroke GAS PISTON system for AR15 type carbines manufactured by Blackthorne Products. This system has a gas block that is machined from 4140 chrome moly steel (NOT cast). This gas block has a mil standard M1913 Picatinny rail machined into the top for easy attachment of accessories. The top of the rail is 1.200" above the centerline of the bore. The system features an ADJUSTABLE gas setting (standard, dirty gun, and cutoff) utilized by simply rotating the gas plug. The hard chrome plated gas piston is made from S7 tool steel for extreme toughness and long life. Also included is a bolt carrier with an integral gas piston lug. This lug is machined right into the carrier, it is all one piece of hardened 8620 steel. The carrier also incorporates an Anti-tilt design to ensure positive function. The handguards included with this system are M4 contour with full heat shields (black only, NOT available in other colors). The top handguard and handguard cap are slotted to accept the piston system. This system is more reliable, cleaner, and runs cooler than other system. This system consists of: Gas block, adjustable gas plug, gas piston, gas piston spring, gas piston tube, one piece semi auto bolt carrier, and bolt spring. The barrel is machined from chrome-moly, high vanadium steel and hardened to a U.S. government Mil-spec of Rc 26-32. The barrel, and all external steel parts, are manganese phosphate finished IAW 5.3.1.2 of Mil-STD-171, the U. S. government's recommended protective finish for steel. This finish not only looks great, it affords complete corrosion protection. These barrels are of Mil-spec M4 contour (.750 under the front sight base) complete with the M203 groove in the front. This contour is the perfect balance between light weight, heat dissipation, and accuracy. The barrel is button rifled with 6 grooves, right hand, 1 / 9"; twist. The 1/9" twist is best because it handles the widest variety of ammunition and bullet weights. The barrel is mounted on a FORGED A3 upper receiver with built in Mil-spec M1913 Picatinny accessory rail, made from certified 7075T6.511 alloy forgings, hardcoat anodized IAW Mil Spec A8625, Type III, Class II, black per No. 37038, Table IX with nickel acetate seal, as per the Mil-spec. The upper features a forward assist and hinged ejection port cover. This upper receiver is complete less bolt/carrier assembly and charging handle. The upper is headspaced and ready for action. The upper is fully assembled and INCLUDES the bolt/carrier group and charging handle. You can get this upper with a CHROME LINED chamber and barrel, just actually order the item # AR-CHROME. You must have the item # AR-CHROME listed on your order and charged $50 in order for you to receive a chrome lined barrel. Do NOT just add it in the special instructions.