Windham Weaponry Multi-Caliber Upper Kit 223 Remington/300 AAC Blackout

Windham Weaponry's Multi-Caliber Upper Receiver Assembly Kit is designed as a unique upgrade for the AR15-type rifle, offering quick and easy caliber changes by simply switching out the barrel, and if necessary, the bolt/bolt carrier and magazine. Add the optic or iron sights of your choice, and this kit is "ready for the range." As with Windham's complete rifles, this kit manufactured to the highest standards from the best materials available. Barrels are chrome-lined for long wear and easy cleaning, machined from 4150 Chrome Moly Vanadium Steel, finished in Black Manganese Phosphate, and rifled appropriately for the intended caliber. Upper Receivers are CNC machined from forged 7075 T6 Aircraft Aluminum and finished in Hardcoat Black Anodize. Bolts are machined from Carpenter 158 Steel. In the detail photo of the underside of the MCS upper receiver, the Barrel Retaining Block has been unlatched, and the Barrel Retaining Arms have been rotated out to release the barrel. Along with unique upper receiver and integral railed forend, this is the "key" to the MCS Quick Change Barrel System. The MCS 1 Kit includes a complete upper receiver assembly with .223/5.56mm caliber M4 barrel assembly; integral railed forend; (with barrel release levers, and barrel retaining block). Additionally, a .300 Blackout caliber barrel assembly is included allowing the change between .223/5.56mm caliber and .300 Blackout caliber by utilizing the same bolt/bolt carrier and .223 magazines. The .223/