Rumors have been floating around since ISOF Range day that USSOCOM was going to issue a Request For Proposals for an M4 compatible upper receiver group capable of firing high pressure 5.56 ammunition as well as currently used M855A1 and Mk262 cartridges. This week Naval Surface Warfare Center Crane released an RFP.
The means of procurement will be Other Transactional Authority. Additional information on this process is available by referencing CSO N0016425SC0001, the Naval Surface Warfare Center (NSWC) Crane Commercial Solutions Opening (CSO).
The Requirement:
USSOCOM is seeking a carbine system to act as a replacement or upgrade for the current URG-I (Upper Receiver Group – Improved). The goal is to integrate advancements in material science and weapon design to provide operators with a technically superior individual weapon system capable of firing both legacy 5.56x45mm NATO and emerging hyper velocity ammunition.
The stated goal of this effort is to extend effective endgames ranges from the current 300 meters out to 600 meters.
Additional details:
The RFP states that “Weapon submissions that address the following technology priorities will benefit during the selection process:”
Hypervelocity Ammunition Compatibility: The ability to accept and reliably cycle both 5.56NATO and hyper velocity 5.56x45mm ammunition is a primary objective. The development of a complete weapon system or conversion kit optimized for hypervelocity ammunition will be a collaborative effort between the government and the proposer. Hypervelocity rounds offer significant performance benefits, including:
Increased Effective Range: Higher muzzle velocity allows the projectile to maintain kinetic energy over longer distances, extending the effective range to 600m+.
Improved Terminal Performance: Enhanced energy transfer upon impact leads to more effective terminal ballistics.
Enhanced Barrier Penetration: The increased velocity and kinetic energy enable the projectile to more effectively defeat body armor, barriers, and other hardened surfaces.
Longevity and Durability: The system must be engineered to withstand the increased chamber pressures and bolt thrust generated by hypervelocity ammunition without compromising the weapon’s service life or operator safety.
Interoperability: The system must remain fully interoperable with USSOCOM’s existing suite of Visual Augmentation Systems and Weapon Accessories (VASWA).
Primary Attributes as Threshold and Objective:
HICAR shall be chambered in 5.56x45mm NATO. (T=O)
HICAR shall be compatible and capable of fit and functioning with the M4A1 lower receiver group without permanent modifications (T); with zero modifications (O)
HICAR shall fire and function with M855A1, Mk262 as well as Government supplied M855A1+ hypervelocity ammunition loaded to 82kpsi (T); with future hypervelocity ammunition designs optimized for projectile velocity and terminal effects on target (O).
HICAR barrel shall be between 11- 12 inches in length, measured from bare muzzle to bolt face (T=O).
HICAR shall not fire when on safe and dropped in accordance with TOP 3-2-045 (T=O).
HICAR shall employ the HUXWRX Flow 556k L In “Black Magic” suppressor (SKU: M3228) to reduce signature (T=O).[1] (this suppressor will serve as a surrogate for HICAR testing, an optimized suppressor requirement will follow in the future)
Secondary Attributes:
Average Mean Radius of 1 MOA (T); 0.5 MOA (O) when fired unsuppressed.[2]
Measured by averaging total of three (3) groups of ten (10) shots each fired by three (3) separate weapons in unsuppressed, manned, supported configuration at 100 meters with Black Hills Mk262 Mod1-C 77gr, PN# MP460556N9-COMMammunition.
No single ten round group larger than 2.5MOA extreme spread (T=O)
Barrel muzzle threaded to 1/2×28 or 5/8×24 threads per inch (T=O).
Weight not to exceed, unloaded and without suppressor, of 8lbs (T); 6.5lbs (O).
Length not to exceed, when measured from the end of the receiver extension to the end of muzzle device, of 31 (T); 28 (O) inches.
Continuously timed and biased M1913 picatinny rail at 12 o’clock minimum of 16 inches in length. (T=O)
Interoperability with all current SOCOM POR Visual Augmentation Systems (VAS) accessories and enablers (T=O).
Recoil shock impulse less than the POR Mk17 7.62NATO to ensure VAS survivability (T=O)
HICAR ergonomics similar to M4A1 (T=O).
HICAR MRBS of 800 (T); 1,600 (O) rounds between stoppages.
HICAR MRBF of 5,000 (T); 10,000 (O) rounds between failures
Cycle and function with M855A1 and Mk262 ammunition (T) cycle and function with current training ammunition to include ball, frangible, and tracer cartridges (O).
Barrel life 8,000 (T); 20,000 (O) rounds.
Measured with M855A1+ ammunition fired as a function of Muzzle Velocity loss of 5% below mean or dispersion above an established threshold, whichever occurs first (T=O).
Trigger pull weight less than 5lbs (T), 3lbs (O)
Selection of fire: Safe, Semi-auto (T) fully Automatic (O).
Cycle and function with Gen3 PMAG Magazines (T=O)[3].
Handguard should minimize deflection and POI shift when under load from a bipod or supported on a barricade (O).
Handguard with M-LOK mounting points at 7 positions radially for mounting accessories and enablers (T=O).
Modular ambidextrous safety lever (O). (“Modular” defined as ability to have a selector lever on left, right or both sides simultaneously)
Ambidextrous bolt catch/bolt release, ambidextrous magazine release, and ambidextrous charging handle (O).
Fencing around the controls to prevent accidental engagement of the magazine release and bolt release mechanisms (T=O).
Single rigid sling point at the rear of the receiver for maritime operations (O)[4].
Resistant to damage from immersion in three (3) feet of seawater for two (2) hours without affecting the weapon’s performance and able to fire within thirty (30) (O); ten (10) (T) seconds after submersion.
Protected with durable corrosion resistant coating in all SOF climatic environments including NBC contaminated environments. Corrosion and abrasion proof coatings to minimize the attraction of dust and contaminants (T=O).
Utilize where possible self-lubricating coatings and minimize buildup of dust, carbon, copper, and debris (O).
Fully functional in all environments from -40 to 165 degrees Fahrenheit (O).
Comply with relevant direct-fire MIL-STD specifications as directed by NSWC-Crane SOCOM Weapons Team (O).
Industry Partner submit to and successfully perform all tests required by NSWC-Crane SOCOM Weapons Team to achieve limited safety release (LSR) from the Navy Weapon Safety Evaluation & Review Board (WSESRB) (O).
Inscribed at position of Government-choosing with Industry Partner, OASW (SO/LIC) & SSO CD&I TOS Team Lethality logos. (Nice touch guys)
Contain markings to include caliber, year of manufacture, and manufacturer identification.
Not rely on any first-order-supply-chain components from adversary countries as defined in the National Defense Authorization Act (NDAA) (O). Any such reliance must be fully documented and mitigated in the Contract Risk Register by Industry Partner (T).
If not already in BASE, Industry to provide industrialization plan to produce HICAR in the United States by the completion of the contract (T). Designed, engineered, and assembled in the United States (O).
A complete HICAR system to consist of the following:
Weapon System, Urban
Heat Mitigation Rail Covers
Buttstock, Multi-Point Adjustable
7x Magpul Gen3 556 Magazines
Field Maintenance Kit, Fix-It Sticks
Field Cleaning Kit
User Manual and Maintenance Manual, hard copy and digital.
The Ammunition
The ammunition used is going to drive this program. As currently configured, neither the M4A1 or USSOCOM’s URG-1 will reliably withstand this new cartridge’s wear and tear. If they would, there would be no reason for this procurement.
Many vendors who are interested in this effort may be disadvantaged due to access to the government provided ammunition and the shirt timelines. White papers must be submitted by 8 June and the government won’t announce those who are invited to a vendor day until 29 June and can’t pitches the specified ammunition until then. They will then have until 15 September to prepare for the Pitch Days where selected vendors will have one-on-ones with the government and must demonstrate their candidate URG on the range.
The big question has been which high pressure 5.56 cartridge they are actually planning to field. It is being referred to as M855A1+ in the RFP and we also know that USSOCOM is planning for chamber pressures in excess of 82kpsi.
The Army has been quietly working on a couple of solutions and SOF another. Even with the fielding of the Next Generation Squad Weapon M7 rifle and M8 carbine, the US Army alone will still have around 900,000 M4/M4A1 carbines in its inventory so enhanced lethality for the M4 platform is in everyone’s best interest. While the Army didn’t adopt the URG-I to improve its service rifle capability, the increased capability of a new high pressure case 5.56 would likely lead to Army interest in fielding an “M4A2” variant using the new URG and appropriate operating system upgrades. In such a scenario, the M4 lower would remain. USSOCOM’s goal is the same, improve the capability of the current M4A1.
Likewise, SOCOM has multiple ammunition improvement efforts afoot including what they are referring to as “Hyper Velocity” ammunition.
Concerns
Aside from access to the ammunition which will become a serious eye opener for those who lack experience with high pressure cartridges, I have a couple of other concerns. The government has stated they are willing to accept Technology Readiness Level 6 proposals which are still in the realm of a science experiment. Additionally, other than what is specified above, there is no proposed timeline for the procurement.
Conclusion
It certainly offers a huge capability increase for US military small arms. This will be an interesting effort to watch and even more so to see what industry proposes and how much of that will be introduced commercially.
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on Wednesday, May 20th, 2026 at 12:11 and is filed under Ammo, SOF, weapons.
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