Sons of Liberty Gun Works Broadsword L89 6mm ARC Upper 18" - No Muzzle Device

The Sons of Liberty Gun Works Broadsword L89 6mm ARC 18-inch barreled upper pushes the 6mm ARC cartridge to its full velocity potential — a billet Broadsword upper receiver, L89 Drivelock rail system with a 15.25-inch seven-sided M-LOK handguard, and a 16-inch Liberty Fighting Barrel extended to 18 inches for maximum long-range precision output, bare-threaded with no muzzle device, without BCG or charging handle.

The SOLGW Broadsword L89 18-inch 6mm ARC barreled upper is a complete upper receiver group built on SOLGW's billet Broadsword upper receiver and L89 Drivelock M-LOK handguard, chambered in 6mm ARC. Features an 18-inch Liberty Fighting Barrel, 4140 steel gas block with nitrided gas tube, Drivelock barrel nut system, anti-rotation tabs, internal dowel pin between upper and rail, and integral steel QD cups at the barrel nut on both sides. Muzzle: bare threaded — no muzzle device. BCG and charging handle not included. Test fired before shipment.

The 18-inch barrel is the precision-optimized configuration for the 6mm ARC — two additional inches of dwell time and barrel length over the 16-inch variant translate to measurable additional muzzle velocity, which flattens the trajectory further, reduces wind drift at distance, and increases the retained energy that heavy 6mm ARC projectiles carry to long-range targets. For shooters building a dedicated precision rifle, hunting platform, or competition upper where maximum cartridge performance takes priority over compactness, the 18-inch barrel extracts more of what the 6mm ARC is capable of delivering. The longer barrel also provides a more forgiving gas dwell time for a suppressor-equipped setup — the additional length between the gas port and the muzzle allows more time for pressure to drop before the bolt begins to unlock, which can reduce the cycling aggressiveness that a suppressor's added back pressure introduces on shorter barrels. The billet Broadsword upper receiver provides tighter dimensional tolerances at the barrel extension interface and upper-to-lower junction than a standard forged upper, establishing the precision foundation that an 18-inch 6mm ARC barrel is built to exploit. The L89 Drivelock system's extended barrel nut, internal dowel pin, and anti-rotation tabs together provide the most rigid two-piece upper-to-handguard connection in SOLGW's lineup, minimizing the micro-movement at the handguard interface that degrades point-of-impact consistency for shooters running laser aiming modules or VAS systems. Bare-threaded muzzle allows the builder to install a suppressor host, precision muzzle brake, or other device timed to the correct position without managing a pre-installed component.

Caliber: 6mm ARC. Barrel: 18 inches, Liberty Fighting Barrel. Upper: billet Broadsword. Rail: L89, seven-sided M-LOK, Drivelock barrel nut, integral steel QD cups both sides, anti-rotation tabs, internal dowel pin. Gas block: 4140 steel, nitrided gas tube. Muzzle: bare threaded — no device. BCG and charging handle: not included. Test fired before shipment.

18-inch barrel extracts maximum velocity from 6mm ARC for flatter trajectory, reduced wind drift, and higher retained energy at long-range targets — the precision and hunting-optimized barrel length for this cartridge. Additional dwell time over shorter variants provides a more forgiving suppressor-compatible gas system starting point. Billet Broadsword upper and L89 Drivelock lockup establish the precision foundation for the 18-inch barrel's performance potential.

The right upper for precision long-range, hunting, and competition 6mm ARC builds where maximum velocity and ballistic performance take priority — Broadsword billet upper, L89 Drivelock, 18-inch bare-threaded Liberty Fighting Barrel, test fired, without BCG or charging handle.