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US Army Develops New Fluted Barrel for M4 Carbine

Two engineers at Picatinny Arsenal have developed a patented spiral fluting for M4A1 barrels to dissipate heat faster and prolong cyclical firing.

US Army Develops New Fluted Barrel for M4 Carbine
Thomas Grego and Adam Foltz, two small arms engineers working at Picatinny Arsenal in New Jersey, have developed a new barrel with a patented spiral fluting to enhance the M4A1 carbine’s performance. Photo courtesy US Army.

While there is a lot of talk about replacing the M4 carbine by the US military, work is still being done to improve its performance. Here is a good example. Thomas Grego and Adam Foltz, two small arms engineers working at Picatinny Arsenal in New Jersey, have developed a new barrel to enhance the M4A1 carbine’s performance. It was specifically designed to reduce the risk of barrel failure or premature ammunition discharge (cook-off failure) by dissipating heat faster than the standard M4A1 heavy barrel. In doing so it facilitates extended cyclical fires.

The barrel features a heavy profile design with spiral flutes in three sections along its length. The spiral fluting both increases surface area while reducing the weight of the barrel. The spacing, thickness, and tapered height of the fluting were all optimized through testing. In addition, the fluting shaves .25 pounds off the barrel. The US Army claims the design allows firing at temperatures as high as 909.5 degrees F, provides a higher cook-off limit, prevents barrel droop, increases the barrel life, and allows an increased sustained rate of fire.

What is interesting is the US Army has been granted two patents on the design. They have received a 15-year design patent and a 20-year utility patent. The US Army states they believe the design may be useful on other weapon systems and is willing to license the design to commercial industry. Brian Metzger, a senior technology manager at TechLink, is facilitating licensing discussions for companies interested in producing the barrel. “The design patent reinforces the utility patent, makes it a complete package for a licensee,” Metzger stated on July 8th, 2020.

Now, fluting barrels to increase surface area to aid cooling is hardly new. It is very early 20th century. Fluted barrels and spiral fluted barrels are widely available already on the US commercial market. I’m curious if this design offers a real-world noticeable improvement. So, I will be interested to see exactly what the US military does with this design, if it is fielded and how it actually performs.


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