How an AR-15 Works

Matt Rittman
10 Aug 202208:33
EducationalLearning
32 Likes 10 Comments

TLDRThis script offers a detailed walkthrough of the AR-15 rifle's operation, from magazine loading and bolt carrier assembly to firing mechanisms and safety features. It explains the process of chambering a round, the role of the forward assist, and the selector's function in single and automatic fire modes. Additionally, it covers the rifle's sighting and adjustment systems, including zeroing the sights for accuracy and the use of alternative optics.

Takeaways
  • 🔫 The 'magazine release' is used to detach the magazine from the lower receiver.
  • 🗞️ Rounds are loaded under high spring force and secured by the 'magazine catch'.
  • 🚀 Pulling the 'charging handle' chambers the first round and compresses the 'action spring'.
  • 🔒 The 'bolt' locks into place with the barrel extension due to the 'cam pin' and 'locking lugs'.
  • 🔄 The 'forward assist' can be used if the bolt fails to fully close, engaging the bolt carrier.
  • 🔫 The AR-15 is ready to fire when the selector is off safe and the trigger allows 'hammer' release.
  • 🔥 The 'firing pin' strikes the primer, igniting the propellant and propelling the bullet.
  • 🌀 The 'rifling grooves' in the barrel impart a stabilizing spin on the bullet.
  • 🌪️ The gases from firing escape through a port and act on the 'bolt carrier key' to cycle the action.
  • 🔄 The 'extractor' and 'ejector' work together to remove the spent cartridge case.
  • ⚙️ Military variants like the M16 and M4 include an 'auto sear' for fully automatic fire.
  • 🔄 The 'burst cam' and 'clutch spring' in the M4 allow for controlled bursts of up to three rounds.
  • 🔚 The 'magazine follower' and 'bolt catch' hold the bolt open after the last round is fired.
  • 🎯 Adjustable sights on the AR-15 allow for aiming at different ranges and windage adjustments.
  • 🔧 The carry handle can be removed for alternative optics, and the stock is adjustable for user comfort.
  • 🛡️ The 'ejection port cover' protects the rifle's inner parts when not in use and opens during firing.
Q & A

  • What is the purpose of the 'magazine release' on an AR-15?

    -The 'magazine release' is used to free the magazine from the lower receiver, allowing for the magazine to be removed or inserted.

  • How are rounds loaded into the magazine of an AR-15?

    -Rounds are loaded into the magazine and held under high force by the magazine spring.

  • What is the function of the 'charging handle' on an AR-15?

    -Pulling and releasing the 'charging handle' chambers the first round by forcing the 'bolt carrier group' to the rear.

  • What is the role of the 'action spring' in the operation of the AR-15?

    -The 'action spring' is compressed when the carrier returns forward, assisting in the movement of the 'bolt carrier group'.

  • How does the 'bolt' interact with the 'barrel extension lugs' during the locking process?

    -The 'bolt' contains several 'locking lugs' that engage with the 'barrel extension lugs', locking into place when it makes contact with the barrel breech face.

  • What is the 'forward assist' and when is it used?

    -The 'forward assist' is used in the rare occurrence where the bolt fails to fully close, allowing the pawl to engage with the notches cut into the bolt carrier and force the carrier forward.

  • What allows the AR-15 to fire continuously in automatic mode?

    -The inclusion of an 'auto sear' and a hook on the back of the hammer allows continuous operation while the trigger is depressed.

  • How does the 'burst mode' on the M4 differ from full automatic fire?

    -In 'burst mode', the 'burst cam' and 'clutch spring' allow the M4 to fire up to three rounds at a time, conserving ammunition and promoting greater accuracy.

  • What is the purpose of the 'ejection port cover' on an AR-15?

    -The 'ejection port cover' is used to protect the inner parts of the rifle from outside elements when not in use and opens automatically when the rifle is fired.

  • How can the front sight post on an AR-15 be adjusted for accuracy?

    -The front sight post can be adjusted up or down for zeroing using a cartridge.

  • What are the two types of apertures on the rear sight of an AR-15 and their respective uses?

    -The rear sight includes two 'apertures'; the larger one is used for short ranges up to two-hundred meters, while the smaller aperture is used for longer ranges.

Outlines
00:00
🔫 AR-15 Firing Mechanism Overview

This paragraph explains the firing mechanism of the AR-15 rifle. It begins with the magazine release and loading process, detailing the role of the magazine spring, magwell, and magazine catch. The charging handle's function in chambering the first round is described, along with the bolt carrier group's movement and the action spring's compression. The bolt's locking mechanism, the cam pin's role, and the forward assist's purpose in rare bolt closure failures are also covered. The firing sequence is outlined, from the trigger's pull releasing the hammer to the impact of the firing pin on the cartridge primer, igniting the propellant and propelling the bullet down the barrel with stabilizing spin from the rifling grooves. The ejection process involving the extractor, ejector, and deflector is described, along with the bolt carrier's return and the cycle's continuation upon trigger release. Military variants like the M16 and M4 are mentioned, highlighting the auto sear and hook for fully automatic fire, the disconnector's role in burst mode, and the auto sear's control over the hammer for continuous operation.

05:02
🎯 AR-15 Sights and Adjustments

The second paragraph delves into the AR-15's sighting system and adjustments. It describes the auto sear's presence in burst mode and the split disconnector's function in semi and burst fire modes, with the burst cam and clutch spring enabling the firing of up to three rounds at a time. The process of the trigger's pull, the burst disconnector's engagement, and the cam's rotation for each round fired in burst mode is detailed. The paragraph also explains the magazine follower's role in holding the bolt open after the last round and the procedure for inserting a new magazine and chambering a round. Sight adjustments for zeroing are covered, including the use of the front sight post, rear sight apertures for different ranges, and the elevation knob for raising and lowering the sight. Windage adjustments using the sight's knob and calibration lines are mentioned. The paragraph concludes with information on alternative optics, adjustable stocks, and the ejection port cover's function.

Mindmap
Keywords
💡Magazine Release
The 'magazine release' is a mechanism on a firearm that allows the magazine to be detached from the gun. In the context of the video, pressing this release frees the magazine from the lower receiver, which is a crucial step in loading or unloading the weapon. It is an essential part of the firearm's operation and is mentioned in the initial steps of handling the firearm.
💡Charging Handle
The 'charging handle' is a component used to manually cycle the action of a firearm. In the script, pulling and releasing this handle chambers the first round, which means it prepares the gun for firing by moving the bolt carrier group to the rear and then allowing it to return forward, stripping a round from the magazine in the process. It is a fundamental part of the firearm's loading procedure.
💡Bolt Carrier Group
The 'bolt carrier group' is a set of moving parts in the firearm that includes the bolt itself. As described in the script, when the charging handle is pulled, it forces this group to the rear, compressing the action spring. Upon returning forward, the bolt strips the top cartridge from the magazine and guides it into the chamber. It is a central part of the firearm's mechanism for loading and firing rounds.
💡Locking Lugs
'Locking lugs' are protrusions on the bolt that engage with corresponding lugs on the barrel extension to lock the bolt in place when a round is chambered. The script mentions that these lugs, along with the cam pin and track in the bolt carrier, facilitate the locking mechanism, ensuring the firearm is ready to fire safely and effectively.
💡Forward Assist
The 'forward assist' is a device used to help ensure the bolt is fully closed and locked. If the bolt fails to fully close, as mentioned in the script, pressing the forward assist plunger allows a pawl to engage with the bolt carrier, forcing it forward until the bolt is fully locked. It serves as a backup to ensure the firearm is properly loaded and safe to fire.
💡Selector
The 'selector' is a part of the firearm that allows the user to choose between different firing modes, such as safe, semi-automatic, and automatic. The script describes how taking the selector off the safe position readies the AR-15 to fire. It is a key component in controlling the operation mode of the firearm.
💡Firing Pin
The 'firing pin' is a component that strikes the primer of a cartridge to ignite the propellant and fire the bullet. In the script, it is described as being struck by the hammer, driven by the hammer spring, which in turn is released by the trigger. The firing pin's action is central to the firing mechanism of the firearm.
💡Rifling Grooves
Rifling grooves are spiraled cuts inside the barrel of a rifled firearm that impart a stabilizing spin on the bullet as it travels down the barrel. The script mentions these grooves as part of the process where the expanding gases propel the bullet, giving it the necessary spin for accurate flight. Rifling is a critical feature for accuracy in firearms.
💡Extractor
The 'extractor' is a device that grips the rim of a spent cartridge case and holds it against the bolt face until it can be ejected. In the script, it is described as part of the ejection process, where the spent cartridge is removed from the chamber after firing. The extractor is an essential part of the firearm's cycling mechanism.
💡Buffer
The 'buffer' is a component that helps to absorb and reduce the force of the bolt carrier group's rearward movement, slowing its return forward. In the script, it is mentioned in relation to the action spring, which returns the bolt carrier forward after the buffer reaches the back of the receiver extension. The buffer plays a role in the smooth operation of the firearm's action.
💡Auto Sear
The 'auto sear' is a component that, when included in a firearm, allows for continuous operation while the trigger is held down, enabling fully automatic fire. The script explains how the auto sear interacts with the selector and disconnector to control the firing sequence in automatic mode. It is a key part of the firearm's modification for automatic firing capabilities.
💡Burst Fire
In the context of the script, 'burst fire' refers to a firing mode where the weapon is capable of firing a set number of rounds, typically three, with a single pull of the trigger. It is a feature that was introduced to conserve ammunition and promote greater accuracy, as opposed to fully automatic fire. The script describes the mechanism involving the auto sear, burst cam, and clutch spring that enables this mode.
Highlights

Pressing the 'magazine release' frees the magazine from the lower receiver.

Rounds are loaded and held under high force of the magazine spring.

Pulling and releasing the 'charging handle' chambers the first round.

The bolt contains several 'locking lugs' that engage with the barrel extension lugs.

The 'cam pin' in the bolt allows it to rotate and lock into place.

The 'forward assist' can be used if the bolt fails to fully close.

With the selector off safe, the AR-15 is ready to fire.

As the trigger is pulled, the 'hammer' is released from the sear.

The 'firing pin' impacts the cartridge primer, igniting the propellant.

Rifling grooves in the barrel impart stabilizing spin on the bullet.

The 'extractor' grips the rim of the spent cartridge case for ejection.

Military variants like the M16 and M4 add a third option for fully automatic fire.

The 'auto sear' and hammer hook allow continuous operation while the trigger is depressed.

A 'burst mode' was introduced to conserve ammunition and promote accuracy.

The 'burst cam' and 'clutch spring' allow the M4 to fire up to three rounds at a time.

The 'magazine follower' pushes up on the 'bolt catch' when the last round is fired.

Using a cartridge, the front sight post can be adjusted up or down for zeroing.

The rear sight includes two 'apertures' for different ranges.

The 'elevation knob' adjusts the sight for different distances.

The carry handle can be removed for alternative optics like holographic sights or scopes.

Many ARs have an adjustable stock that rides along the 'receiver extension'.

The 'ejection port cover' protects the inner parts when the rifle is not in use.

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AR-15Firearm MechanicsWeapon OperationGun SafetyRifle LoadingFiring ProcessAuto SearBurst ModeMilitary VariantsRifle Customization