HM Defense DefenderM556L

The HM Defense DefenderM556L is a lightweight 5.56 NATO patrol carbine engineered for officers who require reduced carry weight without sacrificing duty reliability. Designed around HM Defense’s patented Monobloc barrel technology, the DefenderM556L prioritizes handling, balance, and long-term durability, making it ideal for extended patrol shifts, vehicle deployment, and training-intensive environments.

This platform delivers a familiar AR-15 manual of arms while reducing fatigue during prolonged carry and dynamic movement.

---

Operational Advantages for Law Enforcement

 

• Lightweight configuration reduces officer fatigue during extended shifts

• Patented Monobloc barrel system minimizes gas system failure points

• Mid-length gas system for smooth recoil and consistent cycling

• Standard AR-15 controls reduce retraining requirements

• Patrol-ready 16″ barrel meets general-issue rifle needs

• Modular accessory support for optics, lights, and slings

---

Barrel System

 

• 16″ lightweight-profile 4150 chromoly steel barrel

• Caliber: 5.56 NATO / .223 Remington

• 1:8 twist rate for modern duty ammunition

• Match-grade, button-rifled and honed

• ½×28 threaded muzzle

• Patented Monobloc barrel design with integral gas block

The Monobloc barrel enhances durability and alignment while reducing maintenance requirements—ideal for high-round-count agency use.

---

Upper & Lower Receivers

 

• Forged 7075-T6 aluminum

• Type III hard-coat anodized finish

• Flat-top Picatinny upper receiver

• Mil-Spec lower receiver for compatibility and ease of service

---

Bolt Carrier Group

 

• M16-profile bolt carrier group

• HM Defense patented HMB Bolt, designed to increase bolt strength and service life under duty conditions

---

Handguard & Accessory Integration

 

• Lightweight free-float aluminum handguard

• Full-length Picatinny top rail

• M-LOK mounting surfaces for weapon lights, grips, and accessories

• Optimized for patrol optics and illumination tools while minimizing added weight

---

Controls & Ergonomics

 

• Mil-Spec fire control group

• Standard AR-15 controls for immediate familiarity

• Adjustable stock for armor and shooter fit

• Enhanced pistol grip

• QD sling-ready end plate

---

Weight & Handling

 

• Reduced overall weight compared to standard patrol carbines

• Improved balance enhances target transitions and vehicle handling

• Designed to support long training days and sustained patrol carry

---

Suppressor & Tactical Integration

 

• Threaded barrel supports agency-approved suppressors

• Gas system optimized for reliability with common duty ammunition

• Compatible with weapon-mounted lights, patrol optics, and laser aiming devices

---

Specifications

 

---

Agency Use Case Summary

 

The DefenderM556L is well suited for:

• General-issue patrol rifles

• Vehicle-deployed carbines

• Officers carrying rifles for extended shifts

• Training and qualification programs

• Departments prioritizing reduced weight and handling efficiency