The Sons of Liberty Gun Works M4 L89 5.56 NATO Rifle – 13.7" Pinned (16" OAL) Barrel, Midlength Gas System, Liberty Fighting Trigger, B5 Grip, HUXWRX Flash Hider, Black – M4-L89-13.7-XL / M4L89V213.7XL (UPC: 669185245349) is built from the ground up as a true duty-grade fighting rifle. Designed for professional end users, hard-use enthusiasts, and serious home defenders, this SOLGW M4 L89 combines top-tier components, meticulous tuning, and bombproof reliability in a compact, suppressor-ready package. Bauer Precision+1
Combat-Grade 13.7" Rifle – Pinned to 16" Overall Length
At the heart of the M4 L89 is a 13.7" Sons of Liberty Gun Works V2 combat barrel made from 4150 CrMoV (Chrome Moly Vanadium) steel with a 1:7 twist, high-pressure tested (HPT), and magnetic particle inspected (MPI) for maximum durability and consistency. Bauer Precision
To stay rifle-length legal while maintaining a compact footprint, SOLGW permanently attaches a HUXWRX flash hider to the 1/2x28 threaded muzzle, bringing the overall barrel length to 16" OAL. This muzzle device is pinned and welded at the factory and is specifically chosen to interface with HUXWRX FLOW-series suppressors, making this rifle an ideal host for modern 5.56 cans. Bauer Precision+1
The barrel features a QPQ (quench-polish-quench) corrosion-resistant finish, M4 feed ramp extension, and a properly sized .750 gas block journal that works with SOLGW’s low-profile gas block for outstanding long-term performance. Bauer Precision
Tuned Midlength Gas System & A5 Buffer for Smooth Shooting
The M4 L89 uses a midlength gas system with a melonited stainless-steel gas tube and a nitride-treated low-profile gas block secured with knurled head set screws. This combination delivers soft, reliable cycling and reduced wear across a broad range of ammo, both suppressed and unsuppressed. Bauer Precision+1
For recoil management and reliability, SOLGW outfits the rifle with an A5H2 buffer and Sprinco Green rifle-length action spring inside an intermediate receiver extension. The result is a flatter, more controllable recoil impulse, slower bolt speed, and increased parts life—exactly what you want in a rifle meant for high round counts and hard use. Bauer Precision
Forged 7075-T6 Receivers & L89 DriveLock Handguard
The upper and lower receivers are precision-machined from 7075-T6 aluminum forgings and finished in Type III Class 2 hardcoat anodizing with a non-reflective flat black dye (inside and out). The lower is fully machined with an M16 auto-pocket cut and features “Safe, Fire, Full Auto” pictogram markings plus a Quick Q ambi safety selector for modern ergonomics. Bauer Precision
Up front, the rifle wears the SOLGW L89 upgraded handguard, featuring: Bauer Precision+2Sons Of Liberty Gun Works+2
7-sided M-LOK slots for flexible accessory mounting
Integral steel QD sling cups on both sides
Extended steel barrel nut for rock-solid lockup and improved rigidity
Lightweight construction (around 13 oz) without sacrificing strength
This rail system gives you ample space for white lights, IR devices, foregrips, bipods, and whatever else your mission demands.
Liberty Fighting Trigger, B5 Systems Furniture & Fighter-Ready Controls
The M4 L89 is built to be ready out of the box—no parts swapping required: Bauer Precision+2EuroOptic+2
Liberty Fighting Trigger (LFT): A SOLGW single-stage trigger with a consistent ~5.5 lb pull, tuned for duty use—clean, predictable, and robust enough for real-world abuse.
B5 Systems Grip – Black: Ergonomic angle and texturing for improved weapon control and comfort during long sessions.
B5 Systems Bravo Stock – Black: A duty-grade, adjustable stock offering a solid cheek weld, multiple QD sling points, and low wobble.
Selector & Controls: SOLGW ambi safety selector plus standard AR-15 control layout for fast, instinctive manipulation.
Together, these components ensure your M4 L89 handles like a premium fighting rifle, not a budget build that needs immediate upgrades.
Built for Suppressors & Modern Accessories
Thanks to the pinned HUXWRX muzzle device and midlength gas system, this M4 L89 is optimized as a suppressor host for the HUXWRX FLOW series and other compatible cans. The combination of carefully tuned gas porting, A5 buffer system, and Sprinco Green spring helps keep the rifle controllable and reliable even with backpressure from a silencer. Bauer Precision+1
The L89 M-LOK handguard and forged upper receiver give you a continuous top rail for optics and irons, along with plenty of rail estate for:
Low-power variable optics (LPVOs)
Mini red dot + magnifier setups
IR/laser units for night vision use
Weapon lights, handstops, and more
This rifle is ready to be set up as a duty carbine, home-defense rifle, training gun, or patrol weapon.
Sons of Liberty Quality & Lifetime Warranty
Sons of Liberty Gun Works is known for their philosophy: no-compromise, combat-grade quality. SOLGW emphasizes properly tuned gas systems, high-quality bolt carrier groups, and robust barrels as the foundation of a rifle that can be trusted in the worst conditions. Bauer Precision+1
Every M4 L89 rifle is backed by a Lifetime Warranty that follows the gun, not just the original owner. If you break it doing rifle things, SOLGW will make it right—another reason these rifles are so highly regarded among professional users and serious civilians alike. Bauer Precision
What’s Included
The Sons of Liberty M4 L89 13.7" HUX Rifle ships ready for work with: Bauer Precision+1
(1) 30-round 5.56 NATO magazine
Tactical soft case
SOLGW sticker & patch
Copy of the U.S. Constitution
Lifetime Warranty certificate
Just add your preferred optic and sling, and you have a complete, high-end fighting rifle package.
Key Specs – SOLGW M4 L89 13.7" Pinned HUX
Manufacturer: Sons of Liberty Gun Works
Model: M4 L89 Rifle – V2
Platform: AR-15, semi-automatic
Caliber: 5.56 NATO / .223 Remington Bauer Precision+1
Barrel: 13.7" V2 4150 CrMoV, 1:7 twist, HPT/MPI, QPQ finish, pinned to legal 16" OAL with HUXWRX muzzle device Bauer Precision+1
Gas System: Midlength, Melonited stainless gas tube, SOLGW low-profile gas block (.750) Bauer Precision+1
Muzzle Device: Pinned HUXWRX flash hider (FLOW-series suppressor compatible) Bauer Precision+1
Upper Receiver: Forged 7075-T6 aluminum, Type III hardcoat anodized, engraved T-marks Bauer Precision
Lower Receiver: Forged 7075-T6 aluminum, Type III hardcoat anodized, M16 auto pocket, Quick Q ambi safety Bauer Precision
Handguard: SOLGW upgraded L89 M-LOK rail with integral QD cups, ~13 oz Bauer Precision+1
Buffer System: Intermediate tube, A5H2 buffer, Sprinco Green rifle-length spring Bauer Precision
Trigger: SOLGW Liberty Fighting Trigger (LFT) ~5.5 lb single-stage Bauer Precision+1
Furniture: B5 Systems grip & B5 Systems Bravo stock – Black Bauer Precision+1
Finish: Hardcoat anodized flat black
Capacity: 30 rounds (1 magazine included) Bauer Precision+1
Part Numbers: M4-L89-13.7-XL / M4L89V213.7XL
UPC: 669185245349 Bauer Precision+2capegunworks.com+2
If you’re looking for a truly professional-grade 5.56 NATO rifle with a compact, suppressor-ready 13.7" pinned barrel, tuned midlength gas system, A5 buffer, premium trigger, and bombproof construction, the Sons of Liberty Gun Works M4 L89 M4-L89-13.7-XL / M4L89V213.7XL stands out as one of the most capable options on the market.
The End
