Army Captain Slams New XM7 Rifle As “Unfit,” Sig Sauer Says Otherwise

Army Capt. Braden Trent has caused something of a stir this week, saying that data he has collected points to his service’s new 6.8x51mm XM7 service rifle suffering from serious reliability and other issues, including excessive barrel wear and regular breakages of key components. He claims, based in part on observations of live-fire exercises involving XM7-armed soldiers, that these problems, together with a host of other factors, make the gun “unfit” for its intended purpose. The gun’s manufacturer, Sig Sauer, has strenuously pushed back on Trent’s assertions and outright denied a number of them.

Capt. Trent presented his findings, which come from an unclassified student thesis, at the annual Modern Day Marine exposition in Washington, D.C., on Tuesday. The Army infantry officer is currently attending the Expeditionary Warfare School, part of the Marine Corps University in Quantico, Virginia.

“My project began as a fact-finding mission. I wanted to find out, how does this new product [the XM7] increase soldier lethality and what data can I provide at the unclassified level to help soldiers and leaders alike make better decisions at the tactical, operational, and strategic levels?” Trent said in his presentation at Modern Day Marine. His research, “consisting of in depth historical analysis, testing with experts, ballistics research, extensive dialog with soldiers, industry and leaders,” came “to the conclusion that the XM7 is unfit for use as a modern service rifle.”

What is the XM7 Rifle?

The XM7 is a 6.8x51mm version of Sig Sauer’s increasingly popular MCX Spear family of rifles. Though Sig’s MCX family is a separate development, the core design is derived from the AR-15/M16 pattern family of rifles, and upper receivers from certain versions of the former can be directly paired with lower receivers from the latter with the help of an adapter. The overall configurations of guns in both families are very similar, as are the basic ergonomics and control arrangements.

MCX rifles notably use a gas piston operating mechanism rather than the direct impingement method found on AR-15/M16 types. Direct impingement (DI) involves propellant gases directly blowing into the main action to cycle it, which can more quickly lead to fouling on key components without regular cleaning. Piston systems that keep gas away from a gun’s internal works can offer improved overall reliability in certain circumstances, although they tend to be heavier than their DI counterparts.

The XM7 is one part of the Army’s Next Generation Squad Weapons (NGSW) family of systems, which also includes the 6.8x51mm XM250 light machine gun, the computerized XM157 optic, and various types of 6.8x51mm ammunition. The 6.8mm rounds notably have a hybrid case with a brass body and a stainless steel base designed to allow for improved performance and reduced weight.

Sig Sauer is now delivering XM7s and XM250s, as well as 6.8x51mm rounds, after having won the NGSW competition in 2022, and the guns are being fielded. At the time of the initial award, Sig’s contract for the weapon portion of the NGSW program had a ceiling of nearly $5 billion. The XM157s are being procured separately from Vortex Optics.

Army combat experiences from the Global War on Terror, especially operations in Afghanistan, where reports often emerged of U.S. forces being outranged, helped drive the NGSW program’s core requirement for guns firing larger rounds offering greater range and terminal ballistic performance. Concerns about improving adversary body armor were also a factor.

As of last year, the Army said its “acquisition objectives” included the purchase of 111,428 XM7s, 13,334 XM250s, and 124,749 XM157s. The XM7 and XM250 are in line to replace a substantial portion of the service’s existing M4A1 carbines (an AR-15/M16 family design) and M249 Squad Automatic Weapons (SAW), respectively, both of which are chambered to fire the 5.56x45mm cartridge.

Capt. Trent’s technical criticisms of the XM7

“I’d like to present a technical comparison between the XM7 and the M4A1. There’s a lot of statistics on this page, but the first one I’d like to draw your attention to is total combat weight. Total combat weight is defined as the weight of the weapon, along with a loaded magazine and any accessories that would be expected to be issued to soldiers receiving the system,” Capt. Trent said on Tuesday. “The M4A1 comes in at around eight and a half pounds, which is somewhat lightweight, but still somewhat heavy compared to rifles of old. The XM7, by comparison, comes in at 15.4 pounds.”

“The XM7 has a relatively short barrel length of 13 inches,” he added. “That’s actually an inch and a half shorter than the M4A1.”

It is immediately worth noting here that the Army says the standard barrel length for the XM7 is 15.3 inches, which is longer than the 14.5-inch barrel on the M4A1. Sig does offer the MCX Spear with a 13-inch barrel. How Trent arrived at the “combat weight” figure for the XM7 is also not immediately clear. The rifle weighs 8.4 pounds unloaded with no accessories and 9.8 pounds with just the addition of a suppressor, according to the Army. A loaded 20-round magazine and the XM157 optic would further increase that weight.

“The NGSW program required a velocity of greater than 3,000 feet per second. Shorter barrels have a negative impact on velocity, meaning that an immense power load is then required of the ammunition to reach program requirements,” per Trent’s research. “The outcome is an immense chamber pressure in the XM7, in excess of 80,000 PSI [pounds per square inch]. This causes dramatically increased wear of internal components and ammunition.”

Catridge cases “have literally been ripped apart by the internal pressure of the system,” he added. Ruptured cases in any firearm can cause malfunctions and prompt potential operator safety concerns.

Trent said he observed and/or learned of a number of other serious technical issues after being given the chance to interview “over 150 soldiers, maintainers, and leaders,” as well as inspect a sample set of 23 XM7 rifles, all from the 1st Brigade Combat Team, 101st Airborne Division. 1/101st’s 1st Battalion, 506th Infantry Regiment was the first operational Army unit to begin receiving XM7s and the rest of the NGSW family of systems.

The “most serious issue observed with the XM7 was barrel and rifle[ing] gouging occurring in all samples that had greater than 2,000 rounds through the system,” according to Trent. “It has to be said that 2,000 rounds through a rifle is generally, in the industry, considered to be a break-in period. However, approximately four inches from the muzzle … [and] one inch behind the gas block, a scratch, or in some cases, a gouge is starting to form in the rifling of the system itself. This can lead to all kinds of problems with accuracy and safety.”

In addition, “the XM7[‘s] charging handle has to be pulled all the way to the rear charge the bolt into battery” and “if you attempt to do that, you’ll actually impact the rear of the stock. So soldiers have to pull up and out on the charging handle in order to charge the weapon,” per Trent. “There were three separate cases of the charging handle snapping when pulled with excessive force under adrenaline.”

“It has to be mentioned that the XM7 does have a side charging handle, but this is positioned so close to the face of the soldier that it’s not ergonomically viable and is especially difficult to operate when shooting prone,” he added.

“Next issue observed is the suppressor and the suppressor locking ring. The suppressor locking ring is the device that attaches the suppressor to the rifle,” Trent highlighted. “Soldiers reported that with hand strength, this device could be broken, meaning that a suppressor could not be mounted to the system or could cause catastrophic malfunctions.”

The Army captain said he had observed three suppressors that had suffered catastrophic damage due to this issue during his visit to the 101st Airborne Division.

Trent also pointed out problems encountered with the XM7’s ambidextrous magazine release.

“While seemingly well-intentioned, if you can imagine the rifle at the low ready position in the hands of a soldier or Marine, this would frequently bump into the body armor or chest plates of soldiers in the field, causing the magazine to be released prematurely,” he said. “This was such a problem that some soldiers had actually created DIY [do-it-yourself] solutions to this in an attempt to get around it.”

To underscore his own findings, Trent highlighted comments about the XM7 from the most recent annual report put out by the Pentagon’s Office of the Director of Test and Evaluation (DOT&E) earlier this year. Based on the results of combined operations demonstration and limited lethality assessment in 2024, “the XM7 with mounted XM157 demonstrated a low probability of completing one 72-hour wartime mission without incurring a critical failure,” the unclassified report said, but without providing more specific details.

Operational limitations

Trent further contended that the XM7, even working as intended, is not a suitable standard infantry weapon for the Army due to its weight, bulk, increased recoil, and reduced magazine capacity (20 versus 30 rounds) compared to the existing M4A1. He also argued that evidence continues to show that the majority of infantry engagements occur at ranges of 300 meters or less, negating the increased effective range and improved terminal ballistic performance that the Army has cited as core reasons for adopting the new 6.8x51mm service rifle.

“I was able to observe … a combined arms live fire exercise, or company live fire for those who aren’t familiar,” Trent explained. “The platoon I was tasked with observing was tasked to suppress the objective for the other two platoons of that company to then maneuver and provide effects on the battlefield.”

“Within 10 minutes, the platoon I observed was almost completely out of ammunition after starting the engagement. By 15 minutes, their ability to produce effective suppression had become almost zero,” he continued. “This is after having taken spare magazines for the XM7 from radio operators, medics, platoon leadership, etc.”

“And this can really be drawn down to one major fault in the XM7, and that’s the UBL … or universal basic load. It’s a metric that can be applied to almost any weapon system, and it essentially means the amount of magazines and associated ammunition that a system uses and is expected to be carried into battle,” he added. “So the XM7 [and] the M4A1 actually have the same number of magazines in their UBL seven, but remember, we’re talking about that capacity difference. The total round count a soldier carries into battle with the XM7 is 140 rounds compared to the 210 rounds of the M4A1. Now again, a 70 round difference may not seem significant, but to the soldier in the fight, it absolutely is a difference. Not to mention that every magazine added to the XM7, each 20-round loaded magazine adds another 1.25 pounds to the soldier’s load, meaning that if troops equipped with the XM7 tried to match their old UBLs [in terms of round count], they’re going to have even more weight being carried.”

“The final thing I’d like to mention is the Chief of Army Infantry’s stated goal of a 55-pound total soldier load,” the Army captain noted toward the end of his presentation at Modern Day Marine. “If we just take the XM7 and its seven UBL magazine load, we’re almost at half that weight, and that’s before the soldier is put on body armor, water, a rucksack, or anything else that they’ll need in the fight.”

Trent also conducted his own experiments with the help of the Marine Corps’ Weapons Training Battalion, and using 7.62x51mm M110 and 5.56x45mm M38 rifles as surrogates for the XM7. The M38 is a subvariant of the Marine Corps’ M27 Infantry Automatic Rifle (IAR), which is, in turn, a variant of the HK416. The HK416 is a gas-piston derivative of the AR-15/M16 series.

“The data demonstrates that a heavier system, or [a system with] higher weight and recoil, increases shooter engagement time, both on the first shot and on follow-up shots. A heavier weight and recoil system decreases shooter hit probability at all distances from seven to 300 meters, the standard range of an infantry engagement, and a lighter weight and recoil system enables faster follow-up shots at all distances from seven to 300 meters,” according to Trent.

Sig Sauer’s Rebuttal

Jason St. John, Senior Director of Strategic Products for the Defense Strategies Group at Sig Sauer, and Joshua Shoemaker, the company’s Defense Product Manager for Rifles and Suppressors, provided TWZ with a detailed rebuttal to Capt. Trent’s findings from the show floor at Modern Day Marine this week.

St. John said that Trent had not consulted the Army program office or Sig Sauer as part of the work on his thesis. Sig Sauer did meet with Trent on the sidelines of Modern Day Marine to discuss his findings.

“I believe that Captain Trent had some shortcomings and difficulties in understanding the totality of the NGSW program and some significant blind spots into the progress that the NGSW program has made over the last let’s call it 24 months. By him not having any clarity on any of the engineering change proposal efforts, and understanding of the 101st [Airborne Division’s] fielding efforts, the actual pacing of the program … and really the ongoing product improvement efforts that the program office and Sig Sauer are doing in concert with each other, really clouded his perspective, and I believe his opinions that he represented,” St. John said. “There are significant misrepresentations and holes in those statements [that he made].”

For one, St. John denied that the XM7’s average chamber pressure has been exceeding 80,000 PSI. That at least certain loadings of the 6.8x51mm cartridge, as well as the .277 Fury round it is based on, have maximum chamber pressure ratings of 80,000 PSI has been widely reported.

“It operates in the 77K PSI range, which is higher than legacy ammunition pressures,” St. John explained. “Legacy ammunition pressures average, let’s just call it about 65K PSI. We can go plus three, minus three, we can go actually minus 10, depending on the cartridge. But the benefit of the technology of the Sig Sauer hybrid ammunition is the ability for that ammunition and the development of this weapon system to operate at higher pressures, so that you can get a higher level of performance out of a smaller weapon system.”

St. John added that the XM7 had been tested to safely operate with chamber pressures up to 125,000 PSI and said that any assertions that the gun’s chamber pressure might present risks to the shooter were “patently false.” He also said he was not aware of any case rupturing since Sig Sauer first developed the ammunition before the NGSW program was even formalized, but did not deny the possibility.

“We do significant reliability [testing], but more importantly, we do a lot of safety testing. And one of the things that we do from a safety testing perspective is we do obstructed bore, and an obstructed bore test is really the most catastrophic event that could happen in a firearms incident,” St. Johns explained. “We do it in three different positions. We put a lodged projectile an inch inside of the chamber, we put another round behind it, and we fire it with a lodged projectile. We do that same test with it midway … down the barrel, and we do it at the end of the barrel. If, during that test, we have any sort of catastrophic failure that’s going to lend itself to a safety concern for a soldier, the weapon system is completely redesigned and started over.”

“There has never been an incident with the NGSW with an obstructed bore in our testing where, if that gun had an obstructed bore, which is the high-det[onation], high-pressure, high catastrophic event, where there’s ever been a situation where that rifle has witnessed any potential for causing an issue,” he added.

St. John also rejected the assertion that the XM7’s ambidextrous magazine release is particularly easy to hit accidentally.

“We have redesigned our magazine release to ensure that it has a better form and function, because there was [sic] some situations where our magazine release was slightly out of spec from a parts perspective, and because of that out of specification, the magazine release would unintentionally release the magazine,” St. John did acknolwedge. “That’s been rectified through the U.S. Army engineering change proposal process. We’ve implemented multiple manufacturing inspection processes of that part to ensure that, as that’s identified, that that can’t happen in the future.”

Both St. John and Sig Sauer’s Shoemaker said they were unaware of any instances of the XM7’s charging handle being snapped off.

What Capt. Trent is “more likely referencing is when you charge the charging handle – it’s a user training thing – guys are coming off of the AR[-15/M16] platform on a direct impingement system where that’s tied to the carrier,” Shoemaker said. “This is a piston-driven system. It’s tied on the op[erating] rod. So a little bit of movement up and down. So if you pull on it in a rearward position, it could crash into the back of the stock, if the stock is in a collapsed position.”

“If you pull it [the charging handle] to the rear, normally, it’s not going to interfere with the bustock. If you lift up slightly on it’s not going to interfere with the buttstock,” St. John added. “I have never seen in any evaluation, any testing, or had any field report from any end user of an MCX charging handle snapping from use.”

Shoemaker further asserted that the basic issue of soldiers becoming more familiar with the particulars of operating the XM7’s charging handle has been “overcome with training.”

When asked about Capt. Trent’s description of the XM7’s side-mounted charging handle as “not ergonomically viable,” St. John called that an “opinion” and said that having two charging handles on the gun offers shooters more options depending on the circumstances.

“I honestly don’t know what he’s referencing there,” St. John also said when about the suppressor locking ring issue.

“Barrel life on our rifle exceeds 10,000 rounds. I believe the army requirement was 5,000 rounds. Without physically inspecting the barrel … that he’s referencing, I would say that I don’t think we’ve witnessed anything that he is referencing,” St. John added.

Sig Sauer’s St. John did acknowledge that the XM7 is still evolving as a result of ongoing testing and user feedback, and that Sig expects more changes to the gun to come in the future, as is often the case when a military gets a new weapon system.

“I think that soldiers and citizens should want Sig Sauer, the U.S. [Army] program office to continue that practice of continually evolving and developing and improving their soldiers weapons systems. And I think we anticipate that we’re going to undergo those improvement processes for the next 25 to 30 years,” Sig Sauer’s St. John did also note. “There’s going to be improvements in manufacturing [and] materials processes. The soldiers on the ground and the U.S. Army are going to dictate different operational requirements and standards for the weapons systems, and we’re going to have to react to those modifications that are going to optimize that weapon system as that evolves through time and history.”

“It should be no surprise, in my opinion, that specifically in the infancy of a weapons program that there’s a very aggressive improvement effort to ensure that the Army and the soldiers get the weapon system that they deserve,” he added.

What the XM7’s future might otherwise hold

TWZ has also reached out to the Army for responses to Capt. Trent’s findings, including his assertions about the general operational utility of the XM7 compared to the M4A1.

“The Next Generation Squad Weapons (NGSW) program significantly increases lethality and probability of hit at the squad level,” the Army’s official website on the program declares. “Due to the nature of the NGSW ammunition, the 6.8mm projectile will outperform even the most modern 5.56mm and 7.62mm ammunition. These weapon systems will give Soldiers significant capability improvements in accuracy, range, signature management, and lethality.”

It’s also worth noting that the NGSW program also reflects the end result of decades of failed Army attempts to adopt a new standard service rifle, potentially in a different cartridge than 5.56x45mm, as well as efforts to move away from the AR-15/M16 family. For an armed force as large as the Army, any wide-scale adoption of a new firearm and a new type of ammunition is a huge undertaking to begin with. All new systems go through some degree of teething issues when they are first fielded.

As mentioned at the beginning of the story, NGSW is a multi-billion-dollar effort of major importance to both the Army and Sig Sauer. Just this week, the Pentagon and the Army announced major service-wide restructuring plans that will have immense ramifications for many programs, a number of which are likely to be severely truncated, if not cut outright, in the coming months.

How the Army progresses with the XM7 and the rest of the NGSW program could have implications for other branches of the U.S. military, as well. Given its size, the Army is often a key driver of joint force small arms decisions simply due to logistics factors and economies of scale. Virtually the entire U.S. military, with the notable exception of special operations units, is in the process right now of fielding variants of Sig Sauer’s P320 pistol. The Army selected a P320-based design as the winner of its Modular Handgun System (MHS) competition in 2017. Sig Sauer has faced significant separate criticism around the P320 over serious drop safety issues that the company insists it has resolved. The pistols also suffered teething troubles during initial fielding with the US Army.

Marine officials said separately at Modern Day Marine this week that their service had just recently completed an evaluation of the NGSW family of systems and is now processing the results to determine what, if any, steps forward will be taken. For now, the primary arm of the Marines remains the M27.

“My hope is not that I can provide a definitive answer … it requires further exploration by experts in the field, decision makers in high places, to really explore this,” Capt. Trent did also told members of the Marine Corps Association in a live interview from the floor of Modern Day Marine after his presentation. “I hope that I’ve at least generated conversation that can lead the American military to receiving even more lethal weapon systems and capabilities.”

“My hope is that this just generates further interest and discussion about what are the pros and cons of the system,” Trent continued. “If we are going to remain with the XM7, okay, but how can we address the issues for the system to mitigate risk to soldiers [and] maximize lethality?”

Special thanks to Breaking Defense‘s Ashley Roque for providing audio of Braden Trent’s presentation at Modern Day Marine.

Contact the author: joe@twz.com