How the M4 Evolved and Could Stay in Service till 2040 | Task & Purpose

The M16 and M4 platforms are extremely well known all the world over. The M16 has been the weapon of choice for the US Army since its creation in the mid-1960s. But almost as soon as the US Army issued the M16, they started making changes quietly and ultimately changed over to the M4 platform. This platform has continued to evolve for the US Army and civilians, but not without its share of controversy. Chris Cappy from Task and Purpose walks us through this topic from the beginning to the current day and beyond.

Chris Cappy with M4
Chris Cappy, of Task and Purpose, takes a look at the M4 and its evolution, including the original prototype in the 1960s, and the future of the platform. Chris also discusses the legal issues of the adoption of the M4 versus the M16 and if it was done correctly.


Although the US Army officially issued the M16 in the 1960s, almost immediately they quietly started making changes and revamping the platform. As a point of fact, Chris points out that the M4 prototype was made just two years after the M16 was created.

The M16 platform was extremely popular with roughly 500,000 in existence and over 60 countries adopting the platform. But a survey of 2,600 returning soldiers from the First Gulf War reported that 20 percent of them said their rifle jammed in combat. Chris wonders why the US Army continues to use the platform even after so many mixed reviews.

Since 2001, Colt Firearm, the manufacturer of the M16/M4 for those who don’t know, has been in as many legal battles as the platform has been in real battles. Mostly they’re battling to defend their licensing rights and trying to keep their status as the sole manufacturer of arms for the Army, a position that has been eroding over the years.

The real question in the matter is when the US Army switched over to the M4 from the M16, was it a whole new system, or was it essentially the same? Chris says that if it was a new weapon system, the Army should have held a competition or called for a better replacement. Whether it was a legal change over or not, Chris isn’t sure.

He does say, however, that swapping from M16s to millions of dollars worth of M4 was a backdoor primary weapons switch. Further, the M4A1 modernization saw many improvements to the platform that set it apart from the M16. But how did it start?

XM177 Colt Commando
The XM177 Colt Commando is the early prototype of the M4 platform from the Vietnam War. The Special Forces wanted a more compact weapon, which they mostly got with a 10” barrel and 4” flash suppressor that brought the system to a slightly lower decibel.

Platform Modernization

As Cappy explains, the modernization of the M16 and M4 really started in the Vietnam War with the prototype XM177 Colt Commando. Special Forces wanted a platform that was more compact, and the XM177 had a 10” barrel, which at the time was half the size of the M16. Robb Roy, the designer at Colt, added a 4” flash suppressor on the barrel to bring the overall length up to 14”.

Cappy stresses that the whole point of the new version was to make it as small as possible, so it is unclear why they add that long flash hider that barely worked. He wonders if it was possibly a General that liked the look, or possibly a government requirement to mitigate the sound down to a certain level, and it did bring down the noise levels to almost bearable levels.

The XM177 was a hit with the SF crowd. They got an adjustable buttstock to boot. But ultimately the XM177 was replaced with the XM4 in 1994. Compared to previous models, accuracy and range were negatively affected with the new version. While the XM4 was more compact, and that was readily accepted, the shorter barrel wasn’t up to long sustained periods of fire.

Legal Problems?

A lot of the problems with performance and licensing started with the M4 rollout. In the 1990s, the order for the rifle was limited in numbers so it wasn’t such a big deal, it essentially was a replacement for the MP5. Since that initial limited order, a lot has changed and the Army has been placing a massive amount of orders, making it the primary weapon over the M16.

The numbers started to bother some folks because there wasn’t an open call for replacements which would have allowed for competition. Even with the well-documented issues with the rifle, without competition, Colt was not forced to innovate.

M4 malfunction
The M4 platform went through a revamp and got a shorter barrel and gas system, but it increased the overall pressure of the system. This is where a lot of problems started happening, including jamming and malfunctions. The brightest issue is that the shorter barrel couldn’t withstand long periods of firing and would melt and warp, like in the Wanat, Afghanistan battle in 2008.

The change to the platform was not just swapping it to a smaller barrel. With the shorter barrel, the gas impingement system had to be adjusted, resulting in increased pressures in the system. It went from 10,000 psi up to 17,000 psi, causing more malfunctions. Additionally, it was shortening the rifle’s lifespan to 6,000 rounds. This is the starting point for all the issues, problems, and complaints to roll in.

Unfortunately, in 2008, the incident in Wanat, Afghanistan happened, highlighting the XM4’s issues. In the battle, one unit was surrounded by the enemy, and they fired so many rounds during the firefight that the barrels overheated to the point that some barrels melted and warped.

Future Weapons Options

After the incident in Afghanistan, an official investigation exposed the rifle’s many shortcomings that had been ignored. Things like the shortening of the gas system that was never fully tested. The US Army then turned its eyes to the future of engagements and what a weapon would need.

Chris got his hands on a full-send version of the rifle. He was skeptical but wanted to test it.

  • 7 pounds fully loaded
  • 900 rounds/minute
  • Muzzle velocity 910/second with new steel core ammo
  • Ammo max range is 500 meters

Cappy states that the ammo is most effective on targets up to 400 meters, and that is coming from LTC Jeffrey K. Woods who worked on the new steel ammo program. Chris is a strong proponent of having the full-send option rifle available to troops.

The NGSW (Next Generation Squad Weapon) program seems to be hedging its bets to keep the M4 relevant, even as it seems that they are trying to replace the 5.56 platform with the 6.8. This could be a little bit of the Sunk Cost Fallacy at play or maybe even some sentimentality. Cappy wonders what a reasonable level of quality to achieve for the typical infantryman’s weapon.

The Army seemed to start right away with Colt swapping out the fire control group from the 3-round burst to the full-send group and ambidextrous controls. The trigger has a consistent pull and a heavier barrel that can withstand higher temps, so hopefully, another Wanat doesn’t happen.

M4 full send
For the future of the M4, soldiers are getting platforms with full-send and not just the 3-round burst that was traditional. Thanks to innovations from the Air Force Security Force evaluations, some think the M4 could hold through 2040 and stay relevant.

But Journalists started to notice when the military was requesting large numbers of M4 rifles, something like a swap over to a new system. But where was the competition? Cappy raises the question again if it was a tweak to a system or a full overhaul.

The Air Force Security Forces Center Evaluations investigated the changes to the M4, including the mid-length gas system that dropped malfunctions and doubled the life expectancy of the platform. They took it further and improved the A1, meaning now the rifle could last well through 2040.

Cappy ends the video by circling back to the Colt manufacturing license. People believe that Colt has had primary control over the M4 design for far too long. Colt, on the other hand, thinks they have been getting ripped off by others since the sole license expired in 2009. When the license expired, the US Army got the design rights to the M4 carbine and in 2012, they awarded the contract to Remington the contract. Colt had been trying to block the contract since 2017 but lost. After that mess, the contract was moved to FN and is for 100,000 M4A1 rifles.

For Chris, Colt rested on their laurels for too long and didn’t bother to innovate to stay relevant.

Patti Miller is one of the most awesome females in the tactical/firearm (or any) industry. Imagine a tall, hawt, dangerous Laura Ingalls Wilder type with cool hair and a suppressed blaster and you'll be getting the idea. What's interesting is that in addition to being a willing brawler and intrepid adventuress, she's also an Ent/Ogier level gardener and a truly badass baker.


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