USSOCOM HICAR: 5.56 Carbine to Double the M4 Range

Last updated June 2026 · By Nick Hall, tracks military small arms and service-rifle news for USA Gun Shop

Quick take: US Special Operations Command wants a carbine that reaches twice as far as today’s M4. Its new HICAR requirement, short for Hypervelocity Improved Capability Assault Rifle, asks industry for a short 11 to 12-inch 5.56mm carbine that stays effective past 600 meters, roughly double the practical range of the current URG-I. The trick is a new hypervelocity round loaded to a blistering 82,000 psi. This is a requirement, not a rifle you’ll see on a shelf.

US special operations troops carrying carbines, illustrating the USSOCOM HICAR hypervelocity assault rifle requirement

What it is: HICAR, the Hypervelocity Improved Capability Assault Rifle, a USSOCOM requirement for a short-barreled 5.56mm carbine effective past 600 meters.
Why it matters: It aims to roughly double the effective range of the current special-operations carbine while keeping the gun short, using a new high-pressure hypervelocity 5.56 round rather than switching to a bigger caliber.
What’s next: This is a solicitation, asking industry what’s possible. There’s no rifle, no contract, no winner, and no fielding date yet.
Who it’s aimed at: US special operations forces, who want more reach out of a compact carbine without jumping to a heavier weapon and a new logistics chain.

What HICAR Actually Is

HICAR is a USSOCOM solicitation, a wish list handed to the firearms industry, for a 5.56mm carbine that can reach out past 600 meters from an 11 to 12-inch barrel. It is not a finished program with a chosen gun.

Special Operations Command does this when it wants to know what’s technically feasible before it commits. The headline goal is dramatic: roughly double the effective range of the carbine special operators carry today. And it wants to do that without giving up the short, handy length that makes a carbine easy to run in and out of vehicles, helicopters, and doorways. That’s a tall order, and the round is how they plan to get there.

The 82,000 PSI Round

The key to HICAR is ammunition: a government-supplied hypervelocity load, referred to as M855A1+, run at around 82,000 psi. That pressure is the whole story.

For reference, standard 5.56 NATO runs in the neighborhood of 55,000 to 62,000 psi. Pushing toward 82,000 psi is a huge jump, and it’s the same high-pressure philosophy behind the Army’s new 6.8mm round. More pressure means more velocity, and more velocity means a flatter trajectory and more energy way out at distance. The solicitation also lists the current M855A1 and the Mk262 load, so the gun has to digest existing ammo as well as the new hot stuff. Asking a rifle to run safely at 82,000 psi is the central engineering hurdle here.

From 300 Meters to 600-Plus

The baseline HICAR is trying to beat is the URG-I, the Upper Receiver Group, Improved, which has a practical effective range of around 300 meters. HICAR wants to push that past 600.

The URG-I is the well-regarded upgrade that special operators run on their M4-pattern lowers today, and 300 meters is honest work for a short 5.56. Doubling that from a barrel that’s actually shorter, 11 to 12 inches, is what makes HICAR ambitious. Normally you’d reach farther by going to a bigger cartridge, like the Army did with 6.8mm. SOCOM is betting it can stay in 5.56, keep the gun small, and buy the range back with pressure and velocity instead.

The Engineering Challenge

Running 82,000 psi through a short barrel reliably, shot after shot, is hard on everything: the chamber, the bolt, the gas system, and barrel life. This is the part that separates a wish from a weapon.

High pressure beats up parts and burns out barrels faster, and a short barrel gives the hot gas less room to do its work before the bullet exits. Whoever answers this solicitation has to prove a rifle that’s durable, controllable, and accurate under those conditions. It’s the same fundamental problem the industry is wrestling with across the board right now, from the Army’s 6.8mm guns to new high-pressure commercial ammo. HICAR is special operations asking whether 5.56 still has room to grow.

What Happens Next

Nothing you can buy, and nothing soon. HICAR is a solicitation, the earliest stage of a program, with no down-selected rifle, contract, or timeline announced. Treat it as a signal of where the military is thinking.

Solicitations like this sometimes turn into fielded weapons and sometimes quietly disappear. What’s worth watching is the direction: even after spending billions to move the regular Army to 6.8mm, special operations is still looking for ways to get more out of compact 5.56. If a HICAR-style high-pressure 5.56 ever matures, the technology tends to trickle down to the commercial AR market eventually. For where service-rifle tech sits today, see our coverage of the FN ARKA and our best AR-15 rifles roundup.

Frequently Asked Questions

What is the USSOCOM HICAR program?

HICAR stands for Hypervelocity Improved Capability Assault Rifle. It is a US Special Operations Command requirement for a short 11 to 12-inch 5.56mm carbine that stays effective past 600 meters, roughly double the range of the current URG-I. As of June 2026 it is a solicitation, not a fielded rifle.

How does HICAR aim to double the M4's range?

With ammunition, not a bigger caliber. HICAR is built around a government-supplied hypervelocity 5.56 load, referred to as M855A1+, run at about 82,000 psi. That high pressure drives higher velocity, a flatter trajectory, and more energy at long range, all from a compact 5.56 carbine.

What is 82,000 psi compared to normal 5.56?

Standard 5.56 NATO runs roughly 55,000 to 62,000 psi. HICAR's target of about 82,000 psi is a large increase, in the same high-pressure direction as the Army's new 6.8mm cartridge. Containing that pressure safely in a short-barreled rifle is the central engineering challenge.

What ammunition will HICAR use?

The solicitation lists the existing M855A1 and Mk262 loads plus a government-supplied M855A1+ hypervelocity round loaded to around 82,000 psi. The rifle has to run all of them.

What is the URG-I that HICAR would replace or improve on?

The URG-I, or Upper Receiver Group, Improved, is the upgraded M4-pattern upper special operators use today, with a practical effective range of around 300 meters. HICAR wants to roughly double that from an even shorter barrel.

Can civilians buy a HICAR rifle?

No. HICAR is an early-stage military solicitation with no chosen rifle, contract, or timeline. There is no commercial version. If the high-pressure 5.56 technology matures, it could eventually influence commercial AR-15 designs, but that is speculative.

Why not just use a bigger caliber like 6.8mm?

That is exactly what the regular Army did with its Next Generation Squad Weapon. Special operations wants to keep the compact size, light ammo, and existing logistics of 5.56 while buying back range through higher pressure and velocity instead of a heavier cartridge and rifle.