In the January/February 2015 edition of the Atlantic, retired Army Maj. Gen. Robert Scales argues that the M4, the rifle used by today’s infantry, is deeply flawed and a danger to soldiers in combat zones around the world. Specifically, Scales cites the deaths of nine infantrymen who were killed while fighting the Taliban at a combat outpost near the village of Wanat in Afghanistan. He ultimately blames their deaths on their weapons jamming and compares their experience to incidents that occurred in Vietnam 50 years earlier. Scales’ writes, “Over the next few decades, the Department of Defense will spend more than $1 trillion on F-35 stealth fighter jets that after nearly 10 years of testing have yet to be deployed to a single combat zone. But bad rifles are in soldiers’ hands in every combat zone.”
While the Department of Defense can certainly be accused of misallocating funds while neglecting certain equipment fundamentals, overall, it is Scales’ argument against the M4 that is deeply flawed, not the firearm itself.
Scales references the experience of troops at the 2009 Battle of Wanat as evidence of critical flaws with the modern M4 and and M16 design. “The Wanat story is reminiscent of experiences in Vietnam: in fact, other than a few cosmetic changes, the rifles from both wars are virtually the same,” he argues.
From the Wanat engagement, there are multiple reports of the M4A1 suffering jams and other malfunctions, including melting barrels. But Scales fails to mention the extreme circumstances the weapons in question were used under in Wanat. Several of the soldiers who experienced malfunctions were firing their M4s on “cyclic;” defined as the maximum mechanical rate of fire possible for an automatic weapon if it had an unlimited source of ammunition.
It’s important to note that the recommended rate of fire for an M4A1 is 15 rounds a minute and 90 rounds a minute for emergencies; much lower than the cyclic rate of 700 to 950 rounds per minute. Exceeding these limits is not standard procedure; troops are trained to mainly fire on semi-automatic, reserving full automatic for emergency situations. The troops at Wanat were definitely in such an emergency, as their main fire support weapon systems like the M249 light machine gun and the M240B medium machine gun had gone down, leaving only their M4s to pick up the slack. Few assault rifles --- even the vaunted AK-series weapons with their legendary reputation for reliability --- could have maintained their cyclic rate without quickly malfunctioning. Expecting the M4 to perform like a belt-fed weapon designed for sustain fire is simply unreasonable; regardless, special operations units have adopted heavier barrels more tolerant of higher rates of fire.
When it comes to malfunctions, Scales asserts that the gas-impingement design of the M16 and M4 is the culprit. He recommends using a gas piston system, citing that top-tiered special operation units like Delta Force and SEAL Team Six have adopted the HK416, essentially a piston-driven M4, as their weapon of choice. While piston systems are certainly capable of increasing reliability; they also have their drawbacks. A gas piston can cause the bolt carrier to tilt inside the gun, creating a potentially catastrophic malfunction. Pistons also add more weight to the gun, and can have negative effects on accuracy.
Many of the problems experienced by service members with the M4 can be attributed to improper maintenance. Most rifles are well-maintained at the individual level, but some of the military’s guidelines and training regarding M4 maintenance are outdated. Multiple former special operators who now work in the firearms training industry cite the current issues with the M4 as stemming from improper lubrication, a lack of preventative maintenance, and less than ideal parts. The continued popularity of M4-style weapons in the American civilian shooting and tactical training industries point to institutional problems with the use and care of the M4 in the military. Scales may be right in that the weapon Colt builds may have issues, but there are now dozens of companies building M4-style rifles that are considered highly reliable; the issue may be with the manufacturer rather than the design itself.
Scales also views the short barrel length of the M4 as a “serious disadvantage in modern combat.” Through the lens of Afghanistan, with its longer than average engagement distances, that's a valid point. But if you look at Iraq, with its predominantly urban terrain, a longer barrel would be a huge hindrance. No infantry rifle will be suited to every situation; special operations units have addressed this by issuing different upper receivers with different barrel lengths. The same goes for caliber. There is no caliber suited to every situation. The 5.56x45mm M4, like most assault rifles, is optimized for around 300 meters; the M16 with its longer barrel length is optimized for 400. Different types of 5.56 ammo will provide different results as well: For example, the Mk 262 round was designed for marksmen, and when combined with the right barrel length and rifle, can be effective past 600 meters. It’s a fair assessment that the 5.56mm round is less effective in Afghanistan due to the general longer engagement ranges, and that 7.62x51mm weapons would be better suited to the task. But there are always tradeoffs.
The M4 excels in urban and jungle environments, where engagement ranges are often well within 300 meters. The smaller bullet means more rounds per magazine, and more ammunition carried by service members overall. 7.62mm weapons like the M14 are heavier, and more difficult to maneuver in urban environments. The larger bullets mean less per magazine, and a smaller overall ammo load. The 7.62 also has the potential to overpenetrate; a potential hazard in a urban environments where civilians or friendly troops may be hit if bullets pass through targets or exterior walls. There is no one size fits all bullet; each has a specific use.
Scales mentions the option of switching to a new round for the M4, but the three most viable cartridges on the market today have their shortfalls. 6.8 SPC loses energy at longer ranges, 6.5mm is less effective in shorter barrels, and .300 Blackout has a short maximum effective range. Even ignoring these considerations, the logistics of adopting a new caliber are immense. All the M4/M16 would have to be upgraded, or entirely new guns in the new caliber bought outright. In addition, other weapons using the 5.56 round like the M249 squad automatic weapon would have to been upgraded or replaced in order to simplify logistics.
The horrible experience Scales had with the original M16 is accurate; the gun he used was the product of one of the most dysfunctional and poorly led weapons programs of the 20th century. But he can no longer claim that the current M16A4 and the M4A1 are the same as the rifle he used in 1968. Many improvements --- some cosmetic, others internal --- have evolved the gun into a workhorse of militaries, special operations forces, and civilian shooters. Both internal military studies and inquiries by the press have shown that troops generally like the M4.
Scales is right when he says the M4 can be improved upon; there are always new accessories for the M4 platform being developed, and the military, especially outside of special operations, lags behind adoption of these developments. The M4 could be upgraded with newer “tube” modular hand guards that save weight and are more ergonomic than current “quad rail” systems. Lower receivers with ambidextrous controls could make the M4 easier to operate from either shoulder. New gas blocks could be installed, enabling the use of suppressors on all M4s. And there are plenty of new optics that could save weight, function longer, and enhance the M4 user’s accuracy.
But these improvements have little to do with the overall function or design of the weapon. The U.S. Army has tried to replace the M16 and its variants four times; every time, the Army did not see dramatic enough results to warrant the adoption of a new rifle. The rifle continues to be adopted by foreign militaries not beholden to American weapons procurement politics, and is a favorite of civilian shooters who have a massive number of choices in the marketplace.
In a time of shrinking budgets and controversies over other equipment like camouflage or load-bearing gear, the M4 is probably the last piece of equipment that needs fixing.