Assault Rifles Versus Machine Guns | The Key Differences


It can be confusing to learn all the minute differences between two seemingly identical terms. Assault rifle and machine gun — at a glance — can seem like different terms for the same classification of guns, but that’s not actually the case. There are legal and functional differences between these weapons, but what are they exactly?

The difference between an assault rifle and a machine gun is whether the gun has the capacity for automatic fire or the ability to fire bullets continuously without the need to take an extra step (such as moving a slide, bolt, or lever). Legally, the line between the two remains muddy at best.

This article will take a closer look at the differences between assault rifles and machine guns, including the precise legal and functional differences between the two and their legality statuses.

The Key Differences

Two words can completely change what you’re talking about when it comes to the topic of guns, and those words are “automatic fire.” Assault rifle sounds like a scary term implying that a weapon’s purpose is solely to attack others, but it’s not quite so sinister – mostly, it comes down to selective firing options. 

Assault rifles have multiple firing options that usually consist of: 

  • Semi-automatic fire: where one pull of the trigger fires a single bullet
  • Automatic fire: where holding down the trigger fires a continuous stream of bullets according to the capabilities determined by the mechanical components of the gun 

Different components can cause wildly varying rates of fire that are suitable for different tactical situations. Many so-called assault rifles don’t even have automatic firing capabilities when manufactured for civilians. Or, they need a special conversion kit to gain this ability.

Conversely, the term ‘machine gun’ has much less of a stigma attached to it in today’s world, even though they’re much more what people think of when they think of the capacity to harm and kill. Machine guns differ from assault rifles in that they typically only have automatic fire as the sole firing option.

In modern U.S society, the two terms have been used interchangeably to refer to weapons of war designed specifically to kill human beings as efficiently as possible, leading to controversy and triggering debate in the wake of shooting tragedies caused by spree shooters.

Legality of Assault Rifles and Machine Guns

The legality of assault rifles and machine guns has entered the public consciousness after multiple school shootings and other tragedies perpetrated by criminals in recent decades. These high-profile crimes have sparked heated debates about the merits of being able to own these weapons without significant legal requirements. 

Assault Rifles, Machine Guns, and Rights

A key part of this debate is how to define weapons as assault rifles or — as called in political discussion —  ‘assault weapons.’ Varying components of guns have been called into question as lawmakers have regularly struggled with regulating such weapons without significantly hampering citizens’ right to own firearms, as defined by the Second Amendment in the Bill of Rights.

Rarely is the automatic fire itself called into question because manufacturing new automatic weapons for sale to civilians was banned as part of the 1986 Firearm Owners Protection Act. As a loophole, this allows citizens to purchase automatic guns manufactured before 1986. Before that, fully automatic machine guns were initially banned for civilian purchase and ownership by the National Firearms Act of 1934.

Nowadays, it’s legal to purchase and own a fully automatic gun as long as the purchaser satisfies legal requirements, usually a tax and background check, including fingerprints and photographs. The process can take up to a year per gun.

Today in the U.S, the purchase of semi-automatic guns remains legal in most states. But the legality of this remains a hot topic of debate. Some gun control advocates wish to define assault weapons broadly, and gun rights advocates point out that relatively restrictive laws already bind automatic guns with the most capacity for violence. 

The main problem with restricting gun ownership is how to keep guns out of the reach of criminals without infringing on the Second Amendment rights of the citizens who abide by the law. As of yet, there’s no solution to the satisfaction of both critics and advocates.

States sometimes try to regulate weapons individually, but this usually leads to controversy and more debate over how to define guns as fit for civilian usage. Other components of the national gun debate are background checks and mental health checks.

Gun Accessory Legality

Surprisingly, gun accessories have also been pointed to as part of the problem leading to excessive gun violence in the United States.

High-capacity magazines have frequently been identified as a large part of the problem, allowing someone to fire a large number of bullets before having to reload. Sometimes, accessories that artificially simulate automatic fire for functionally semi-automatic weapons receive blame — so-called ‘bump stocks’ that use weapons’ recoil to assist faster firing are a big one.

Other accessories facing scrutiny are better grips and muzzle brakes, but they’re not nearly as crucial compared to whether a weapon has the capacity for automatic fire or not. Another hugely controversial part of the gun debate is the existence of kits that allow a user to convert a semi-automatic weapon to fully automatic, effectively rendering laws useless.

Designating the Common Rifles

When you think of assault rifles and machine guns, there are likely a few iconic examples that immediately pop to mind. Some of these are the AR-15, at the heart of the assault weapon controversy, and the AK-47, one of the most well-known guns in history. Others are the M16, once the standard firearm of the U.S military, and Uzis, previously one of the best submachine guns in the world.

Is an AR-15 a Machine Gun?

At the heart of the gun debate for its use or misuse.

The AR-15 is not an automatic gun and therefore not considered a machine gun. While gun conversion kits allow a user to convert the gun to allow for automatic fire, the AR-15 is not manufactured with an automatic firing option.

However, many gun owners enjoy various benefits such as rust resistance, lightweight, and versatility in accessory compatibility.

Is an AK-47 a Machine Gun?

This one is trickier than AR-15s because different versions with the same name have been manufactured at different times.

An AK-47 is not technically a machine gone. While AK-47s were once created with automatic firing capabilities, the only variants in production today in the U.S are produced with semi-automatic capabilities. Of course, conversion kits make automatic fire relatively simple to achieve.

Originally, AK-47s were created with semi-automatic and automatic firing options and continue to be used widely as the gun of choice in wartorn countries throughout the world.

Is an Uzi Considered a Machine Gun?

Uzis were automatic at one time and continue to be produced and used by many countries. Still, in the U.S, only semi-automatic versions of the weapon are manufactured and sold. As with any gun, though, conversion to automatic isn’t difficult and only requires a user to purchase a conversion kit.

Final Thoughts

While legal definitions continue to vary and debate continues to rage about suitable regulations to minimize gun violence in the U.S, the actual definitions are fairly clear-cut. Assault rifles may have the capacity for automatic fire, but machine guns can only fire automatically. Conversion kits to easily modify semi-automatic weapons into automatic variants further worsen the confusion.

For more, don’t miss What Makes a Rifle a DMR? (With 9 Examples).

Jim James

Hey, I'm Jim and the author of this website. I have always been interested in survival, fishing, camping, and anything in nature. In fact, while growing up I spent more time on the water than on land! I am also a best-selling author and have a degree in History, Anthropology, and Music. I hope you find value in the articles on this website. Feel free to contact me if you have any questions or input!

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