Aberdeen Proving Ground, Maryland –– Behind the walls of the Combat Capabilities Development Command’s Army Research Laboratory a team of engineers is testing and tweaking a new breech and barrel design that doubles the muzzle velocity of standard-issue rifles.
Among their goals is hypervelocity for extended range lethality from standard-sized weapons, and full-sized rifle velocities with firearms that are half the weight, half the length, and hold more ammunition than the Army’s M4 carbine.
In future combat, U.S. soldiers and unmanned systems will defeat soft targets with very short machine guns, or hard targets at long ranges with higher levels of kinetic energy.
One of the weapons being developed is an ultra-light-weight machine gun still in the R&D phase, which will feature a high-capacity magazine (around 50 rounds).
The prototype’s barrel is a mere 10 inches long.
Experimental firings were conducted in March with a cartridge that contained less than a gram of propellant (15 grains).
The muzzle velocity was over 2,900 feet per second, outperforming similar short-barreled weapons like the FN P90, which rates at 2,350 feet per second at the muzzle.
“The goal is to get rifle-like velocities out of a very small weapon that is high capacity, that’s either adaptable for room-clearing or confined spaces,” said Zac Wingard, a mechanical engineer at the lab. “Like you’re getting in and out of vehicles or a subterranean environment, but also applicable for remotely operated systems, so think like perimeter security or ground robot or even a drone.”
The enabling technologies the Army has invented could be used in any firearm (semi-automatic pistols, belt-fed machine guns, or bolt-action sniper rifles), including a new breech and bolt design, which allow smaller cartridges to achieve enhanced ballistic performance.
But to withstand the increase in chamber pressure and still be able to cycle, the standard bolt and locking lugs mechanism that holds the cartridge would need to be substantially increased in size and weight—adding to the already overburdened soldier.
So, the conventional designs were replaced by a new bolt assembly that twists in and out of the barrel breech like a screw, said Alex Michlin, the Army research engineer who invented it.
“The powder used now in most ammunitions can be tweaked, so it runs at a higher pressure, but the guns can’t handle it,” Michlin said. “That’s why we designed the new breech, so we can take existing propellant and turn the knob all the way up to 11.”
And under the increased pressure, the metallic shell casings tend to stick in the barrel. So, Michlin also invented a collet to surround the cartridge when seated in the chamber. The tapered wedges of the collet reduce extraction forces by 50%, leaving more energy for cycling the bolt.
And the barrels being tested are also new, sort of.
Tapered-bore guns propel a swageable projectiles propelled down a constricted caliber barrel for high muzzle velocity and reduced aerodynamic drag. This technology was first demonstrated in the 1930s for medium caliber, high-velocity anti-tank guns that were fielded by Germany during World War II. After the war, all tapered bore gun efforts failed to achieve projectile structural integrity, but Army researchers have succeeded and are improving on the tapered-bore design to boost velocity, delivering more energy on target.
But the U.S. Army’s new 24-inch prototype barrel produced muzzle velocities of 4,600 to 5,750 feet per second.
The combustion chamber pressure was increased from 65 ksi to 100 ksi (100,000 pounds per square inch), almost double the pressure seen in the M4 carbine.
Army researchers are also pursuing tapered bore guns to improve the ballistics of very compact, high capacity weapons. By refining projectile aerodynamics and a high capacity prototype gun, Army researchers are realizing a new class of firearms under 15 inches in overall length.
In partnership with the Army Research Laboratory’s Technology Transfer and Outreach Office, TechLink is searching for capable industry partners that can transition the firearm and projectile designs into production for sales to military or civilian customers.
Private companies can leverage the Army’s research by licensing the patent rights from the Army or partnering with the lab through a Cooperative Research and Development Agreement.
“These are disruptive technologies built for a real requirement, lethality, and that means there’s interest in transitioning it to the warfighter because they enable products that outperform what’s currently available,” said Brian Metzger, a senior technology manager at TechLink. “And because we’re the partnership intermediary, we can help companies of all sizes collaborate with the Army.”
Companies with licensing-related inquiries, or interest in cooperative research, can contact Brian Metzger at firstname.lastname@example.org or 406-994-7782.