Windham Weaponry's Multi-Caliber .300 Blackout/7.62x39 Upper Receiver Assembly Kit will quickly upgrade any Mil Spec 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 3 Kit includes a complete upper receiver assembly with a .300 Blackout caliber M4 profile barrel assembly; integral railed forend; (with barrel release levers, and barrel retaining block). Additionally, a 7.62x39mm caliber barrel assembly is included allowing the change between .300 Blackout caliber and 7.62x39mm caliber by utilizing 7.62 bolt/bolt carrier and the included 7.62x39mm caliber magazine. The 7.62x39mm caliber barrel assembly is complete with railed gas block, gas tube, and A2 flash hider. Note these 7.62 bolts are marked with three (3) rings behind the locking lugs so as not to be confused with the .223 caliber bolt.