Alexander Arms Upper Kit Features The Alexander Arms Upper Kit pairs a 12 inch barrel with the 50 Beowulf cartridge giving builders a compact hard-hitting option for close range work on an AR-15 pattern lower. At just 3 lbs the upper kit keeps the overall rifle weight manageable despite the larger bore diameter of the Beowulf cartridge. The 49/64-20 thread pattern at the muzzle is proprietary to the Beowulf platform so builders should plan to pair it with compatible muzzle devices from Alexander Arms. This upper kit allows an existing AR-15 lower to gain the stopping power of the 50 Beowulf without building a dedicated rifle from scratch. Alexander Arms pioneered the 50 Beowulf cartridge specifically for AR-platform rifles and this upper kit reflects that engineering heritage in a ready to install package. Builders looking to diversify their lower receiver s capability can swap between calibers simply by changing upper assemblies and this kit provides that option with a true big bore round. The 12 inch barrel length keeps the overall rifle short and maneuverable well suited to home defense or close range hunting applications. The Alexander Arms Upper Kit is available for sale at GrabAGun for AR owners who want to add 50 Beowulf capability to their platform. Alexander Arms Upper Kit Specifications Manufacturer: Alexander Arms Model: Upper Kit Caliber: .50 Beowulf Barrel Length: 12 Thread Pattern: 49/64-20 Weight: 3 lbs Available At: GrabAGun