B. King's Firearms M4 Mod-0 5.56 NATO Rifle | 16" Barrel | 7075-T6 Aluminum | Made in USA

Duty-Grade Engineering. American Manufacturing. Precision Without Compromise.

The B. King's Firearms (BKF) M4 Mod-0 5.56 NATO Rifle is engineered for shooters who demand exceptional craftsmanship, dependable performance, and premium components. Built as an advancement over the standard BKF lineup, the M4 Mod-0 series is designed to exceed traditional military specifications through precision machining, enhanced controls, and high-quality American-made components.

Proudly sourced, manufactured, and machined in the USA, the M4 Mod-0 features premium 7075-T6 aluminum receivers manufactured to tight tolerances for a solid upper-to-lower fit and consistent functionality.

At the heart of this rifle is a 16-inch 4150 CMV steel barrel, chambered in 5.56 NATO, featuring a 1:7 twist rate, nitride finish, and mid-length gas system. The barrel is equipped with a pinned low-profile gas block and a Breek Arms Plan B Sentinel Caged Flash Hider.

The M4 Mod-0 also incorporates a 4.5-pound two-stage trigger, an A5-style 9-position buffer system with a Sprinco green spring, and enhanced ambidextrous controls.

Its precision-machined upper receiver features a thermal-fit design, while the 15.25-inch free-floating M-LOK handguard includes multiple QD sling attachment points, Picatinny rail sections, and anti-rotation tabs for a secure handguard-to-receiver interface.

Additional premium components include a C158 nitride bolt carrier group, high-pressure tested (HPT) and magnetic particle inspected (MPI), a Breek Sledgehammer ambidextrous charging handle, B5 SOPMOD stock, and B5 Systems Type 23 pistol grip.

Backed by BKF's Lifetime Warranty and 1 MOA accuracy guarantee with match-grade ammunition, the M4 Mod-0 reflects the manufacturer's commitment to quality, precision, and long-term reliability.

Key Features

• American-Made Construction: Proudly sourced, manufactured, and machined in the United States.

• 7075-T6 Aluminum Receivers: Precision-machined to tolerances exceeding traditional mil-spec standards.

• 16-Inch 4150 CMV Barrel: Chambered in 5.56 NATO with a 1:7 twist rate and nitride finish.

• Mid-Length Gas System: Features a pinned low-profile gas block and mid-length gas tube.

• 4.5-Pound Two-Stage Trigger: Premium trigger system included with the enhanced M4 Mod-0 combat control kit.

• A5-Style Buffer System: 9-position 7075 aluminum buffer tube assembly with Sprinco green spring.

• Enhanced Ambidextrous Controls: Includes an ambidextrous safety selector, enhanced bolt catch, and extended magazine release.

• Thermal-Fit Forged Upper Receiver: Manufactured from 7075-T6 aluminum for precise component fit.

• 15.25-Inch M-LOK Handguard: Free-floating design with QD mounting points, Picatinny rail sections, and anti-rotation tabs.

• Premium C158 Bolt Carrier Group: Nitride-finished, HPT/MPI inspected, with Sprinco extractor and ejector springs.

• Breek Sledgehammer Charging Handle: Ambidextrous charging handle with black finish.

• Breek Arms Plan B Sentinel Caged Flash Hider: Pinned-and-welded muzzle device.

• B5 Systems Furniture: Includes B5 SOPMOD stock and Type 23 pistol grip.

• 1 MOA Accuracy Guarantee: Manufacturer-guaranteed accuracy of 1 MOA or better with match-grade ammunition.

• Lifetime Warranty: Backed by B. King's Firearms.

Premium Components and Construction

16-Inch 4150 CMV Nitride Barrel

The M4 Mod-0 features a 16-inch 5.56 NATO barrel manufactured from durable 4150 chrome-moly-vanadium steel.

Built to BKF specifications by a top-tier barrel manufacturer, the barrel incorporates a 1:7 twist rate, nitride treatment, and a mid-length gas system.

BKF states that its pinned gas block barrel configurations are rated for full-automatic use and guarantees 1 MOA or better accuracy with match-grade ammunition.

Precision-Machined 7075-T6 Receivers

The upper and lower receivers are manufactured from high-quality 7075-T6 aluminum and machined to tight tolerances.

The thermal-fit forged upper receiver is designed to provide a precise interface between critical components, while the receiver construction reflects BKF's emphasis on durability and manufacturing consistency.

Enhanced M4 Mod-0 Combat Controls

The rifle includes BKF's enhanced combat control kit, featuring a 4.5-pound two-stage trigger, ambidextrous safety selector, enhanced bolt catch, and extended magazine release.

These components distinguish the M4 Mod-0 from more basic AR-15 configurations.

Premium Bolt Carrier Group

The M4 Mod-0 is equipped with a C158 nitride bolt carrier group that undergoes high-pressure testing and magnetic particle inspection.

Sprinco extractor and ejector springs are incorporated into the assembly, reflecting BKF's emphasis on component quality and durability.

Free-Floating M-LOK Handguard

The 15.25-inch duty-grade handguard features M-LOK attachment slots, multiple QD sling mounting points, and Picatinny rail sections at the 3, 6, and 9 o'clock positions.

Anti-rotation tabs and premium mounting hardware provide a secure interface between the handguard and upper receiver.

B5 Systems Furniture

The rifle comes equipped with a B5 SOPMOD stock and B5 Systems Type 23 pistol grip, providing established ergonomic components from a recognized firearm accessory manufacturer.

Product Specifications

Included with the Rifle

• BKF M4 Mod-0 15.25" Builder Set

• BKF Enhanced M4 Mod-0 Combat Control Kit with 4.5 lb Two-Stage Trigger

• BKF 16" 5.56 NATO Mid-Length 4150 CMV Nitride Barrel

• BKF A5C-Style 9-Position 7075 Buffer Tube Assembly

• Breek Sledgehammer Ambidextrous Charging Handle

• BKF M16 C158 MPI/HPT Bolt Carrier Group

• Sprinco Extractor and Ejector Spring Kit

• BKF Pinned Low-Profile .750 Gas Block

• Mid-Length Gas Tube

• Breek Arms Plan B Sentinel Caged Flash Hider

• B5 SOPMOD Stock

• B5 Systems Type 23 Pistol Grip

• Plano Carrying Case

• Manufacturer Warranty Card

• Test-Fire Casings

• BKF Promotional Items

American-Made Quality Backed by BKF

B. King's Firearms manufactures the M4 Mod-0 series with a focus on precision, durable materials, and strict component standards.

The manufacturer backs the rifle with a lifetime warranty and guarantees 1 MOA or better barrel accuracy when using match-grade ammunition, subject to applicable warranty and accuracy conditions.

B. King's Firearms M4 Mod-0 at TCOB Armory

The BKF M4 Mod-0 5.56 NATO Rifle combines American-made construction, premium components, and precision manufacturing in a duty-grade AR-15 platform.

From its forged 7075-T6 receivers and 4150 CMV barrel to its enhanced controls, premium bolt carrier group, and B5 Systems furniture, the M4 Mod-0 reflects BKF's commitment to quality and craftsmanship.

Available at TCOB Armory, where we take pride in offering quality firearms, trusted manufacturers, and knowledgeable customer service.

TCOB Armory | Quality Gear. Trusted Service.

All firearm purchases and transfers are subject to applicable federal, state, and local laws. Background checks and FFL transfer requirements apply where required.