The U.S. Special Operations Command (USSOCOM) is looking for industry partners to design a new carbine intended to replace or improve the M4A1 URG-I, with a requirement to extend effective 5.56 mm engagement ranges to 600 meters.

The effort, known as the Hypervelocity Improved Carbine (HICAR) program, was disclosed in a solicitation posted on the federal procurement site SAM.gov earlier this month. 

“Special Operations Forces (SOF) require the ability to provide effective fire on targets with their primary 5.56mm carbine out to 600 meters and beyond,” USSOCOM said. “This weapon system will allow an operator to effectively engage targets at extended distances while maintaining the portability and ergonomics of a lightweight carbine.” 

Among the listed specifications, the carbine would feature a barrel length between 11 and 12 inches and an unloaded weight not exceeding 8 pounds without a suppressor, with a target weight of 6.5 pounds if achievable.

The system must also remain compatible with existing M4A1 lower receivers without permanent modification and integrate with SOCOM’s current accessory suite.

The requirement further specifies compatibility with both standard M855A1 and Mk262 ammunition as well as higher-pressure “hypervelocity” 5.56×45 mm rounds under development. 

USSOCOM stated that the system must be designed to endure the higher chamber pressures and bolt thrust produced by hypervelocity ammunition without reducing service life or compromising operator safety.

Documentation notes the use of the HUXWRX Flow 556k suppressor as a test surrogate during evaluation.

White papers are due June 8, 2026, and Pitch Day will be held September 15–16 at Fort Moore’s Parks Range in Georgia.