Gorilla Machining AR-15 SLICK SIDE BIG BORE .450 BUSHMASTER | .458 SOCOM | .45 ACP and 12.7x42 | Aluminum Raw Stripped Upper Receiver
Ejection port opening is .665? wide for use with 458 SOCOM, 375 SOCOM, 450 Bushmaster, 12.7×42 etc, but can also be used for smaller calibers such as 5.56.
Upper Receivers mount and house the barrel, handguard, and gas system in an AR-15 or LR-308/AR-10. Custom upper receivers vary from Side Chargers, and Skeletonized uppers, to Rigidity Reinforced or 'Lite' receivers, where certain features such as the forward assist and brass deflector are removed to streamline the design. This also applies to most Pistol Caliber Carbine upper receivers with special ejection door cuts made specific for 9mm or .45ACP.
About this Upper: Gorilla Machining Slick Side .450 Bushmaster/.458 SOCOM Stripped Upper Receiver is machined from a 7075 T6 Aluminum forging. This .450/.458 Upper Receiver is machined to fit into any standard multi cal lower receivers and features an expanded ejection port opening. This upper is a great option for other large-bore calibers like the .450 Bushmaster, .458 SOCOM, .45 ACP, and 12.7x42.
Material: 7075-T6 Aluminum - 7075-T6 Aluminum is a high-strength alloy metal with great ductility, toughness, and resistance against fatigue. 7075-T6 was standardized for use in Aerospace equipment and aircraft. The Suffix T6 is a temperament treatment to increase the overall toughness and strength of the Aluminum. 7075-T6 Aluminum was chosen for the AR-15 platform for its ease of manufacturing, lightweight properties, and strength.
Style: Mil-Spec - Mil-Spec is the standard for the United States Military for reliability, commonality, reduced cost, and meeting the requirements of a service rifle. 'Mil-Spec' is the essential technical requirement for military-unique materiel or substantially modified commercial items.
Finish: Anodized - This upper receiver is anodized, this process increases the thickness and hardness of the natural oxide layer on the surface of the metal parts. This increases the corrosion and wear resistance of the Upper Receiver.
Caliber compatibility: This upper receiver will work with Big Bore calibers such as .450 Bushmaster, .458 SOCOM, .45 ACP, and 12.7x42
Top Section: Flat Top Rail - This upper receiver features a full 1913 Picatinny rail for the additional Optics installation and Iron Sight installation.
Anti-Rotation Tab compatibility: This upper receiver will allow the installation of handguards with anti-rotation tabs incorporated into their design.
- Brand: Gorilla Machining.
- Model: GM_BBR-1
- Platform: AR-15
- Type: Forged
- Material: 7075-T6
- Style: Mil-Spec
- Caliber Compatibility: Big Bore - .450 Bushmaster, .458 SOCOM, .45 ACP and 12.7x42
- Allows Anti Rotation Tabs: Yes
- Upper Section: Picatinny Rail
- Finish: Raw
- Forward Assist Compatible: No
- Forward Assist Pin Type: none
- Dust Door Compatible: No
- M4 Feed Ramps: Yes
- Color: Aluminum
AR-15 Slick Side Big Bore
Uppers and lowers for the AR15 can typically be interchanged between brands. If your rifle has a unique receiver, you may have problems putting it together. Any upper receiver designed for use with the AR15 platform will be compatible with any lower receiver manufactured to meet or exceed military specifications. One of the reasons why the AR-15 is so popular is because of its adaptability. Modifications and combinations are limitless, whether you go for a larger 50 BMG bolt-action or a more manageable 5.7 FN upper. An AR-10 upper is not compatible with a standard AR-15 lower. While some components may be interchangeable, the receiver base and bolt carrier group are built to separate specifications.