The Rock River Arms LAR-15M CLB Complete Upper, .458 SOCOM, 16" Chrome Moly Bull Barrel, Black Aluminum Receiver, 13" M-LOK Handguard, Beast Brake (SOC0820V1, UPC 842834101306) is a heavy-hitting AR-15 upper built for shooters who want big-bore stopping power with Rock River’s proven reliability. Designed to pin directly onto any standard mil-spec AR-15 lower, this complete upper lets you turn your rifle into a devastating .458 SOCOM platform for hunting, defense, or range fun with minimal effort. Palmetto State Armory+2Ammunition Depot+2
Big-Bore Power: .458 SOCOM for AR-15 Platforms
Chambered in .458 SOCOM, this LAR-15M CLB upper brings serious energy and large-diameter projectiles to the AR-15. Originally designed to increase terminal performance from the AR platform, .458 SOCOM is known for:
Heavy bullets and excellent close-to-midrange impact
Strong performance on hogs, deer, and other medium-to-large game
Impressive stopping power for specialized defensive or tactical roles Palmetto State Armory+1
Because it’s a complete upper, you can swap from 5.56/.223 to .458 SOCOM simply by changing uppers (and using appropriate magazines), without buying a whole new rifle. Palmetto State Armory+1
16" Chrome Moly Bull Barrel – Precision & Durability
At the heart of this upper is a 16-inch chrome moly bull barrel engineered for strength and accuracy. Ammunition Depot+2Palmetto State Armory+2
Key barrel features:
Bull barrel profile for added rigidity and tighter shot-to-shot consistency
Chrome moly steel construction for excellent barrel life and durability under heavy loads
1:14" twist rate, optimized for stabilizing typical .458 SOCOM bullet weights Ammunition Depot+2rockriverarms.com+2
Black finish that matches the upper receiver and handguard for a clean, tactical look RK Guns+1
This setup gives you a robust, accurate barrel that’s purpose-built for the hard-recoiling .458 SOCOM cartridge.
RRA Beast Brake – Taming .458 SOCOM Recoil
To help manage the punch of .458 SOCOM, Rock River Arms equips this upper with their RRA Beast Brake muzzle device. tacticalshopcenter.com+4Ammunition Depot+4Palmetto State Armory+4
Threaded 5/8x32 to match the barrel
Multi-port brake design that redirects gases to reduce felt recoil and muzzle rise
Helps you get back on target faster for quick follow-up shots
On a big-bore AR, a quality brake makes a big difference in comfort and controllability—especially during extended range sessions or when shooting from awkward field positions.
Forged Aluminum Receiver – Mil-Spec Compatible
The LAR-15M CLB Complete Upper uses a forged A4-style aluminum receiver, finished in black to match most AR-15 lowers. firearmsdepot.com+2alpinerange.com+2
Compatible with standard AR-15 mil-spec lowers
Flat-top Picatinny rail for mounting optics, red dots, or BUIS
Designed as a drop-on solution—just pin it to your lower, add sights/optic, and you’re ready to go MidwayUSA+2Palmetto State Armory+2
This makes it ideal both for finishing a new build and for quickly swapping calibers on a favorite lower.
13" Lightweight Aluminum Free-Float M-LOK Handguard
Up front, this Rock River Arms .458 SOCOM upper features a 13-inch lightweight aluminum free-float handguard with M-LOK slots. tacticalshopcenter.com+3Ammunition Depot+3Palmetto State Armory+3
Handguard benefits:
Free-float design helps maximize accuracy by keeping pressure off the barrel
M-LOK slots along the handguard give you flexible mounting for bipods, foregrips, lights, lasers, and QD sling attachments
Extended 13" length provides plenty of real estate for support-hand placement and accessories without adding excessive weight
Combined with the flat-top receiver rail, you get a continuous optics and accessories platform well-suited to both hunting optics and tactical setups. Palmetto State Armory+1
Complete Upper – Includes BCG & Charging Handle
Unlike some stripped uppers, the SOC0820V1 is sold as a complete upper assembly:
That means no hunting for compatible big-bore parts—you get a ready-to-run top end that can be installed on a compatible lower as soon as it arrives (following all safety procedures and local laws).
Low-Profile Gas Block for Reliable Cycling
The Rock River Arms LAR-15M CLB upper uses a low-profile gas block tucked neatly under the free-float handguard. tacticalshopcenter.com+3Ammunition Depot+3rockriverarms.com+3
Keeps the front end clean and snag-free
Supports reliable cycling with the .458 SOCOM round
Allows full-length handguard coverage for maximum accessory mounting space
This system is tuned to deliver dependable performance with quality .458 SOCOM ammunition when properly gassed and maintained.
Ideal For: Hunters, Big-Bore Enthusiasts & AR Builders
The Rock River Arms LAR-15M CLB Complete Upper .458 SOCOM (SOC0820V1) is an excellent choice if you:
Want a big-bore AR-15 upper for hogs, deer, and other close-to-midrange game
Need a factory-built, ready-to-run complete upper with matched BCG and charging handle
Prefer a bull barrel and free-float M-LOK handguard for accuracy and versatility
Appreciate Rock River’s reputation for quality parts used by hunters, law enforcement, and serious shooters Palmetto State Armory+2Palmetto State Armory+2
Whether you’re upgrading an existing rifle or building a new big-bore hunting rig, this upper gives you serious capability with minimal guesswork.
Key Specs – Rock River Arms LAR-15M CLB Complete Upper .458 SOCOM
If you’re ready to step into the world of big-bore AR performance with a trusted, factory-complete package, the Rock River Arms LAR-15M CLB Complete Upper .458 SOCOM SOC0820V1 delivers rugged construction, serious stopping power, and modern M-LOK versatility in one ready-to-mount unit.
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