The XM7: Everything Old Is New Again

Despite some growing pains, the M16 and its derivatives have successfully served the United States military since 1969. The rifle, like any weapon, isn't perfect and doesn't excel in every role. As is tradition with established state armies, the United States Army developed an obsessive focus on the roles the M16 and its derivatives don't excel at and demanded a new rifle that could do everything. Multiple competitions have been held to replace the M4. Heckler and Koch even came close to winning the coveted role with its XM8 rifle until that program, the OICW program, was canceled. The latest program, the NGSW program, finally resulted in a winner, the Sig Sauer XM7 rifle. Now that a new rifle has been chosen, the growing pains have begun. What's interesting about these growing pains is that they look awfully familiar to anybody who read up on the history of the adoption of the M-16.

“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.”

As the article notes, it's not clear how Capt. Braden Trent, the man who presented the criticisms in this article, came to these values. What is clear is that the XM7 when kitted out with its standard optic and suppressor and spare magazines weighs more than the M4A1 with its standard kit. The XM7 shares this issue with the M14. One reason the military replaced the M14 with the M16 is because the M14 with its standard kit weighed a lot. There's a limit to how much a human being can carry. By reducing the weight of the rifle and its ammunition, the M16 allowed soldiers to carry more ammunition than they could with the M14. The XM7 uses a new cartridge that is similar in dimensions and weight to the 7.62x51mm cartridge used by the M14. As a consequence a soldier can't carry as much ammunition.

“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.

Of all the criticisms cited in the article, this one is probably the most reminiscent of the M14 and the most consequential. United States soldiers in the Vietnam War faced North Vietnamese and Viet Cong soldiers armed with AK-47s. During the period where the M14 was the standard infantry rifle, a rifle squad was composed of 11 soldiers. Two of those soldiers had M14E2s, which were select fire. Everyone else had a semi-automatic only M14. The communist Vietnamese soldiers quickly taught the United States soldiers that firepower, the amount of shots a soldier can get off in a period of time, is king on the modern battlefield. While the 7.62x39mm cartridge is technically less powerful than the 7.62x51mm cartridge and while the AK-47 is less accurate than the M14, the mass of bullets a communist Vietnamese soldier could put in the air dwarfed that of a United States soldier. Quantity has a quality all its own as the quote often misattributed to Joseph Stalin goes. This fact made the United States Army generals very mad because they still held marksmanship above all else and they fought hard to keep that fiction alive.

The M16 allowed a United States soldier to deliver the same firepower as a communist Vietnamese soldier. The smaller 5.56x45mm cartridge used by the M16 allowed soldiers to carry more ammunition. The lower recoil made the M16's automatic fire controllable. The fact that the 5.56x45mm cartridge wasn't as powerful as the 7.62x51mm cartridge was irrelevant. A large mass of weaker bullets is more effective in most modern battlefield scenarios than single aimed stronger bullets. By relying on a larger cartridge, the XM7 necessarily reduces a soldier's ammunition capacity and therefore reduces the amount of time they can stay in a fight. I also suspect that the greater recoil with make that limited firepower less effective. Hopefully the XM7 is at least more controllable than the M14E2 when using automatic fire.

The M14 wasn't without its merits. While it wasn't suitable as a general infantry rifle in a post-AK-47 world, it stuck around because it filled a number of niche roles. One weakness of the M16, which is shares with all assault rifles, is effective range and terminal ballistics. The 7.62x51mm cartridge, being a full power rifle cartridge rather than an intermittent cartridge, can reach further and hit harder than a 5.56x45mm cartridge. Furthermore, it can penetrate through more material and remain lethal. The XM7 fires the new 6.8×51mm cartridge (designated as the .277 SIG Fury by the SAAMI), which attempts to further enhance those qualities of the 7.62x51mm cartridge. With a maximum specified chamber pressure of 80,000 psi, the 6.8x51mm cartridge can push a 135 gr bullet out of a 16" barrel at 3,000 fps. Gravity affects everything equally. If you want to make an object go further before it returns to the earth, you need to make it move faster. By accelerating a projectile up to 3,000 fps, the XM7 can reach further than the M14. The further travel distance also makes the bullet's flight path flatter. All things being equal, a 6.8x51mm projectile fired from an XM7 should reach further and hit harder than either a 7.62x51mm from an M14 or a 5.56x45mm from an M4. The question is whether that matters in general use.

During the Global War on Terrorism, United States soldiers periodically found themselves outranged in open country. This reemphasized the value of the designated marksman rifle (DMR). The idea behind a DMR is simple. Give one or two soldiers in a squad a high precision rifle equipped with magnified optics that uses a cartridge that can reach out and touch somebody past 300 or so yards. If the squad comes under fire from an opponent outside of the M4's typical effective range, let the guy(s) with the DMR handle it. With its 6.8x51mm cartridge and a standardized optic, the XM7 could be utilized as a DMR (depending on the accuracy of the rifle). But a rifle squad's overall firepower diminishes if every soldier is carrying a DMR because a cartridge fit for a DMR role isn't fit for an assault rifle role due to factors explained previously. Herein lies the problem with designated the XM7 as the standard infantry rifle. It returns the rifle squad to the days of the M14 in terms of capability. Everyone in the squad can potentially reach a target past 300 yards but the overall squad is capable of delivering less firepower than a squad equipped primarily with assault rifles like the M16. A squad equipped with XM7 rifles will be unable to deliver firepower on par with a squad equipped with AK-47s. This matters because the AK-47 is still the dominant rifle in non-NATO countries. Russia and China, two countries cited to justify the move to the XM7, still use variants of the AK-47 platform.

Firearm technology is mature. Advances since the end of World War II have largely been evolutionary instead of revolutionary. The AK-47 was probably the last revolution in firearms and even it was an evolutionary design. The revolutionary aspects were how easy it was to mass produce and how widespread it became. Those two aspects allowed small communist paramilitary forces to equip themselves with fully automatic rifles that could be controlled by people of small stature (compared to the size of the average American). That fact is what made firepower the king of the infantry battlefield. Nothing revolutionary has happened in the firearm world since then. Standardization of the XM7 is the result of a military so hyper focused on a handful of niche scenarios that is forgot about the most common use case for an standard infantry rifle on the modern battlefield. I'm sure graft also played a major part in standardization of the XM7, but that's a topic for another day.

The article cites a number of mechanical weaknesses and failures of the XM7. I'm not going to highlight those because they're growing pains. Every new standardized military weapon suffers from growing pains and they can be addressed over time. My primary criticism of the XM7 is the doctrine surrounding its adoption. It's a battle rifle. Battle rifles were already proven ineffective as a general infantry rifle after the AK-47 brought the assault rifle to the modern battlefield. If the United States military successfully follows through with standardizing on the XM7, I'm sure it'll relearn the lessons outlined here from the M14. Then it'll undertake a number of new projects to replace the XM7 and eventually settle on an assault rifle not dissimilar in capabilities to the current M4. Everything old is new again.