Moriarti AR-10 .277 SIG Fury 20" SOCOM Upper – 15" Slim M-LOK, Predator Brake

20" .277 Fury SOCOM Upper: Specs & Features

The AR-10 .277 Fury 20" SOCOM Upper with 15" Slim M-LOK Handguard is a purpose-built, precision long-range upper receiver assembly designed for shooters who want modern .277-caliber performance in a standard AR-10 / DPMS-compatible platform. Featuring a 20" Parkerized SOCOM-profile barrel, 1:7 twist, and 4150 CMV steel, this build delivers a powerful, flat-shooting cartridge with exceptional ballistic efficiency—ideal for medium- to long-range hunting, distance shooting, and tactical applications.

The assembly includes a billet 6000-series aluminum DPMS low-profile upper, a 15" slim M-LOK aircraft-grade handguard, and a predator muzzle brake for superior recoil control. It is fully assembled, properly headspaced, and test-fired for guaranteed function.

Key Features:

• 20" Socom Contour Barrel: Made from 4150 CMV steel, hardened to 26-32 RC for durability and stress-relief. The barrel features a 1:7 twist for precise stabilization of projectiles and is chambered in .277 SIG Fury (commercial SAAMI pressure) for superior long-range performance.
• Muzzle Brake: Includes a black predator muzzle brake with 5/8-24 threads, designed to reduce recoil and muzzle rise, aiding in faster target acquisition and follow-up shots.
• Receiver: The .308 low-profile DPMS upper receiver is crafted from solid billet 6000 series aluminum and finished with a black hard coat anodized finish for added durability and corrosion resistance. It comes with a forward assist and ejection port cover installed.
• Gas System: The rifle-length gas tube combined with the .750" low-profile gas block (made from 4140 steel) provides reliable gas flow while resisting corrosion. Perfect for long-range shooting.
• Handguard: The 15" slim design M-LOK handguard is made from 6061-T6 aircraft quality aluminum, providing a lightweight, durable, and flexible mounting platform for accessories. The anodized black finish adds an extra layer of protection against wear and corrosion.

• Fully Assembled and Test Fired: This upper assembly comes fully assembled and has been test-fired to ensure proper cycling and functionality right out of the box.

  IMPORTANT SAFETY WARNING — READ BEFORE USE

  This upper is chambered for commercial-pressure .277 Fury ammunition ONLY.
  Do NOT use 6.8x51 NATO / high-pressure hybrid-case military ammunition.
  Military 6.8x51 operates at significantly higher chamber pressures and can cause catastrophic firearm failure. Only use SAAMI-spec .277 Fury brass-case ammo.

Note: Images may not be an exact representation of the product.

FAQ

What ammunition can I use?

Use commercial SAAMI-spec brass-case .277 SIG Fury ammunition, such as SIG 150 gr factory loads. Do not use 6.8x51 military or high-pressure hybrid-case (80,000 psi) loads.

What lower receiver does this upper fit?

It is built for DPMS-pattern (LR-308 style) AR-10 lower receivers (DPMS low profile). Check your lower's pattern before ordering, since large-frame AR dimensions are not fully standardized.

Is the upper test fired?

Yes. It ships fully assembled, headspaced and test fired.

Related: .277 SIG Fury / 6.8x51 uppers · all AR-10 upper assemblies