M4 vs AR15: Any Actual Difference?

Why Should You Know The Difference between an M4 and AR15?

It’s perplexing when you compare the M4 to the AR15, the M16, and the dozens of varieties of each with their own letter and number combinations to indicate their exact flavor of what is essentially the same thing.

Even worse, some gun enthusiasts enjoy criticizing newcomers for using incorrect naming practices, which just serves to exacerbate the situation. Our article today will compare the differences of these two very similar firearms to help avoid confusion, especially for those new to the industry.

M4 vs AR15: How Do They Compare?

An AR-15 is a semi-automatic rifle with longer handguards and longer barrels than the M4, which is a fully automatic weapon with shorter handguards.

Despite having identical-looking receivers, the M4 has better feed ramps than the AR-15. While M4 has a carbine buffer with a six-position stock making it more modern than AR-15 semi-automatic rifles, AR-15s have longer rifle buffer tubes with stock.



  • Numerous accessories
  • Superior modular ergonomics
  • Lightweight
  • hardly any recoil


  • High maintenance
  • Magazine sensitive



  • Very adaptable
  • Simple to use and regulate
  • High capacity for ammunition
  • High precision even from a distance
  • Easily maintained


  • Difficult to operate with one hand
  • Expensive

Origins of the Rifles

History of AR-15

In Hollywood, California, George Sullivan established ArmaLite as a branch of Fairchild Aircraft Corporation. Eugene Stoner joined the business as the lead engineer not long after it was founded.

The US and nearly everyone else started looking for a new service rifle to replace their current standards very soon after World War II. A new cartridge that everyone could agree upon came along with it.

The Infantry Board Service Rifle Trials began evaluating a new standard issue military rifle for the US in 1952. In 1954–1955, Stoner and his crew created a powerful military rifle that was 7.6251 NATO chambered.

In testing a year later, it would face off against the T44 (which would eventually become the M14), the T47 from Springfield, and the T48 (a copy of the FN FAL).

The ArmaLite design was groundbreaking at the time. The AR-10 was made mostly of plastic and aluminum, and it only weighed 6.85 lbs empty. The T44 and T48 both weighed 9.2 and 10.2 pounds, respectively.

However, the testing went dreadfully wrong. Sullivan requested that a new aluminum/steel barrel be used for the submitted weapons despite Stoner’s vehement protests. The barrel ruptured while being tested. The US Military would never completely forgive the AR-10 for this failure.

ArmaLite’s story did not finish here. In 1957, the T44 became the M14 for the Army.

After the M14 entered Vietnam, things were less than ideal. General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC), ordered a new assault rifle that same year based on battle reports from American military advisers and special forces in Vietnam. Something that can reach a US army helmet at 500 yards while being compact and light.

ArmaLite made the hasty decision to redesign, scale down, and submit the AR-10 for review.

Here comes the AR-15.

The AR-10 and AR-15’s fundamental design components are essentially the same. The AR-15 is merely a scaled-down variant, but all of the functional components are the same. Although the AR-15 is the fundamental design and the origin of the entire movement, the AR-15 never ever existed.

ArmaLite was unable to complete the lengthy and difficult process of testing and adoption of the AR-15. ArmaLite sold Colt the rights to the AR-15 name and design in 1959. The Colt 601 was the first rifle built using the AR-15 concept, and it was released by Colt in late 1959. High-velocity shots are fired by the select-fire rifle.

A great hit was 223 Remington. The American special forces groups in Vietnam were among the first to use Colt 601 rifles in actual battle. Colt’s AR-15/601 was swiftly accepted by the Airforce in 1962. After a few more years, the Army and Marine Corps finally adopted it as the M16A1 in 1969.

History of M4

There was a demand for a shorter variant of the AR-15/Colt 601/M16 almost immediately after it was put into use. The AR-15/Colt 601/M16 was 39 inches long from muzzle to buttplate and had a fixed buttstock.

That’s considerably less than the M14’s 44 inches, but it’s still quite a distance for helicopter pilots, vehicle crewmen, or jungle fighting. Colt’s response was to shorten the barrel by 5 inches, giving it the moniker Model 605B CAR-15. Though not ideal, this version had a fixed buttstock.

Nevertheless, it was used by the US Navy SEALs as early as 1964. However, in order to maintain the reliability required, the AR-15 requires more modifications than simply cutting the barrel length. This would be discovered through field testing by Colt and the military.

The military refused Colt’s request for funding and time to conduct a study since the Vietnam War was about to come to a conclusion. In 1970, the CAR-15 Commando production line was shut down. However, the XM4 was the only weapon used to replace Colt Commando carbines in special forces units until the late 1980s.

Colt would continue to develop a smaller AR-15/M16 long into the 1980s, so this wasn’t the end. Some of these extremely early M16 Carbines would be used by US Special Forces as well as special forces organizations abroad, including the Armed Forces of the Philippines, Malaysia, and other nations.

The M16A2 was created when the US Marine Corps asked Colt to modify the M16A1 with several modifications to strengthen the rifle and change the barrel twist rate. These modifications also affected Colt’s carbine line, which gave rise to the Model 723 M16A2 Carbine.

Delta Force used their 723 carbines to great effect and loved them. The C8 Carbine was created for the Canadian Army in 1983 by Diemaco, a Canadian business that manufactured weapons in the M16 design under license from Colt.

The US Army requested Colt to create their own version in 1984 after noticing how excellent the 723 and the C8 were. Testing began right away, and within a year, “XM4” experimentation carbines were in the possession of special forces. Even though the military adored this new carbine, it took until 1994 for it to be adopted as the M4.

Closer Look at the Differences


The M4 is available as a compact semi-auto rifle called the Armalite Rifle 15. Semi-auto rifles prepare for firing and load the cartridges into the chamber automatically, but the trigger must be pulled manually to fire.

M4 is classified as a select-fire carbine, in contrast. M4 has three different firing modes: burst, semi-auto, and full auto fire.

Velocity and Effective Firing Range

The AR-15’s superior speed over the M4’s is another noteworthy distinction between the two rifles (XM177 Air Force version). The other rifle’s velocity is 2,970 ft/s, whereas the AR can travel up to 3,300 ft/s. The AR bullet moves three times as quickly as a typical handgun bullet.

The M4 has a wider firing range than the AR does. The M4’s effective firing range is 550 yards, while the AR-15’s maximum range is only 500 yards.

Official Permission

The official approval between the AR-15 and M4 differs noticeably. The use and possession of AR-15s by civilian shooters is permitted, subject to some barrel length limitations. Personal uses like hunting and self-defense are permitted.

On the other hand, the M4 cannot be owned by citizens because it is only for use by the military and air force. To obtain the same weapon, you can purchase a mil-spec bottom and identical handguards.

Stock Configuration

One of the most adaptable guns available is the AR-15. It contains a range of possibilities, from add-ons to any significant components you may imagine. You can alter the stock configuration so that your rifle looks good and performs well. M4 can also be somewhat changed.

Gas Tube

The M4’s gas tube is smaller than the AR-15’s. The tube and barrel’s lengths are proportional. The longer gas tube of the Armalite Rifle 15 makes it simpler to tackle the recoil problem. However, because the tube is shorter, the pressure can become an issue. To prevent this, the M4 includes a modified feed ramp.


M4 barrels are shorter than those of AR-15s. According to the ATF, the allowable length of an AR-15’s barrel is 16 inches. To be lawful, any barrel smaller than 16 inches must possess certain documentation, such as an SBR tax stamp.

In contrast, a short barrel like 14.5 inches is acceptable for them to utilise because the M4 is intended for use by the military and the air force. An under-barrel grenade launcher is also included.


The two rifles’ receivers are nearly identical, although the M4 has modified feed ramps and an auto sear. Receivers on more recent M4s are flat-top. The lower receiver of the AR-15 does not contain an auto sear or third trigger pinhole, unlike the M4. It’s because the AR-15 is not an assault rifle or an full auto weapon.

Buffer Tube

When it comes to buffer tubes, there is a distinction between the two. Long, fixed stock buffer tubes are a feature of AR-15s. The M4 has a carbine buffer with a six-position stock and a collapsible stock.

A stock that encloses the buffer and spring can be attached to the rifle using the buffer tube. The spent rounds will be ejected by the bolt carrier before it loads the next one.

AR-15 vs M4 Similarities

The parallels between M4 and AR-15 are unmistakable because M4 is a derivative. Both the top and lower receivers’ internal components are similar. The trigger and trigger assembly, as well as the bolt and bolt carrier group, are comparable. Additional similarities include the charging handle, handguards, and rail systems.

Most of the time, you can swap out the components between the two weapons. There is a striking similarity between the two firearms’ structural elements. The two firearms were made in America, the country that produces strong rifles.

M4 vs AR-15: Which is Better?

based on what we’ve seen. The M4 is superior to the AR-15. More advancements in technology made the M4 more up to date, useful, and dependable. Because of this, the US Military decided to use this military weapon rather than the M16.

Even though the M4 is superior, citizens cannot own it because it is a full-automatic fire weapon. But there aren’t many differences between the same version of these weapons. You can only get an AR-15 without the full auto by purchasing and upgrading it with a shorter barrel and M4 handguards.

Frequently Asked Questions

Can the AR-15 upper fit the M4 lower?

Yes, it is possible to attach an AR-15 upper to an M4 lower. The M4 lower will accommodate the AR upper. You may fit the top section of your AR in an M4 lower because the inner workings of AR-15s and M4s are essentially identical. However, the M4 will not be full auto because the AR lacks a sear.

Are AR-15 and M4 parts interchangeable?

Yes, the components for the AR-15 and M4 are compatible. Since the M4 is an adaptation of the AR-15, the parts that fit in both rifles are essentially identical.

The M4’s majority of components and ammo can be used with the M15s, and the AR-15s can be modified. When it comes to civilian firearms and military weapons, there are, however, relatively few distinctions and restrictions.

Can an M14 barrel fit an AR-15?

Yes, an AR-15 will fit an M4 barrel. The M4 is an AR-15 that is shorter so that it can fit, as we have already stated. However, because the M4 has a short barrel, obtaining one requires paying an SBR tax and filling out a tonne of paperwork. In order to prevent damage, you must also make sure that the caliber is the same.

Which AR-15 model is closest to M4?

The rifle that is closest to the M4 is the Colt AR-15. Since the M4 is made similarly to this kind of rifle, some parts, particularly the inner parts, are interchangeable. At first appearance, you might mistake the Colt AR-15 for an M4 with a shorter barrel, but after using it, you’ll see the differences.

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