How to Troubleshoot AR15 Malfunctions

How to Troubleshoot AR15 Malfunctions

This article will explain how to correct the most common and odd malfunctions to bring your modern sporting rifle/pistol back in good working order. The topics we will cover will go in chronological order of difficulty level. First, let’s start with a basic understanding of how an AR15 operates. Once you understand how the system operates, all malfunctions interrupt this cycle. Knowing what stage is interrupted and how to fix the malfunction will allow you to troubleshoot your AR15 better and see the status of the (why).


  1. Feeding
  2. Chambering
  3. Locking
  4. Firing
  5. Unlocking
  6. Extracting
  7. Ejecting
  8. Cocking


  • As the bolt carrier group assembly moves, compressing the buffer spring assembly and clearing the top of the magazine, the magazine spring expands to place a round of ammunition in the travel path of the bolt carrier group assembly.
  • The buffer spring assembly expands and moves the bolt carrier group forward, allowing one of the two bottom bolt lugs to strip a round of ammunition out of the magazine.
  • The round of ammunition is guided into the chamber by the feed ramps located on the barrel extension, and the forward motion of the bolts lugs into the barrel chamber.
  • Six events happen at nearly the same time to accomplish locking.
  • Bolt makes contact with the breach of the barrel
  • Buffer spring is still expanding forward
  • Cam pin clears the guide channel.
  • Following the cam track, the cam pin rotates the bolt to align the bolt lugs behind the extension lugs
  • Extractor grabs the ammunition’s case head
  • Ejector spring is compressed
  • The shooter squeezes the trigger, and the trigger pivots on the trigger pin.
  • The nose of the trigger is depressed and allows clearance for the bottom of the hammer
  • The hammer is free to rotate on the hammer pin, and the hammer spring thrusts the hammer forward
  • Hammer hits the head of the firing pin, and the firing pin travels forward and strikes the primer in the ammunition.
  • Primer ignites, causing the powder to ignite, creating a gas
  • The expansion of the gas forces the bolt reward, but it cannot move due to the engagement of the bolt and barrel extension lugs.
  • The bullet is forced down the barrel.
  • When the heel of the bullet passes the gas port, the trapped gas has a new pathway, and the gas port redirects a volume of gas into the gas block.
  • Gas block transfers the gas to the gas tube; the gas travels down the gas tube towards the gas key
  • with the bolt still locked, the gas impacts the gas key and forces the bolt carrier reward.
  • Cam pin follows the cam track and rotates the bolt to unlock as the gas pushes the bolt carrier reward, compressing the buffer and spring.
  • Once the bolt is fully unlocked, the ammunition casing travels with the bolt carrier group due to the extractor lock on the case head.
  • Once the used ammunition case clears the ejection port, the empty case no longer has resistance. The ejector plunger spring expands and forces the casing away
  • The cocking ramp on the bottom of the bolt carrier forces the hammer down to be locked by the trigger disconnect
  • The bolt carrier group has compressed the buffer spring within the stock, and the cycle of operation starts all over again with 1. feeding.  


Procedural or mechanical failures of the rifle, magazine, or ammunition cause malfunctions. Pre-firing checks and serviceability inspections identify potential problems before they become malfunctions. This section describes the primary categories of malfunctions. If at any time you feel the headspace of the barrel is incorrect, STOP use and contact the manufacturer of the firearm.


A stoppage is a failure of an automatic or semiautomatic firearm to complete the cycle of operation. The shooter can apply immediate or remedial action to clear the stoppage. Some stoppages cannot be removed by immediate or remedial action and may require weapon repair to correct the problem—a complete understanding of how the weapon functions is an integral part of applying immediate action procedures.


Immediate action involves quickly applying a possible correction to reduce a stoppage without performing troubleshooting procedures to determine the actual cause. Apply immediate action only once for a stoppage. If the rifle fails to fire again for the same malfunction, inspect the firearm to determine the cause of the stoppage or malfunction and take the appropriate remedial action. The critical word SPORTS will help the shooter remember the steps for immediate action:

(1) (S)lap gently upward on the magazine to ensure it is fully seated and the magazine follower is not jammed.

NOTE: When slapping up on the magazine, be careful not to knock a round out of the magazine into the line of the bolt carrier, causing more problems. Slap only hard enough to ensure that the magazine is fully seated. Ensure that the magazine is locked into place by quickly pulling down on the magazine.

(2) (P)ull the charging handle fully to the rear

(3) (O)observe the ejection of a live round or expended cartridge

NOTE: If the FIREARM fails to eject a cartridge, perform remedial action

(4) (R)lease the charging handle; do not ride it forward

(5) (T)ap the forward assist assembly to ensure that the bolt is closed

(6) (S)queeze the trigger and try to fire the rifle


Remedial action is the continuing effort to determine the cause of a stoppage or malfunction and attempt to clear the stoppage once it has been identified. To apply the corrective steps for remedial action—

(1) Point the firearm down range or in a safe direction

(2) Try to place the weapon on SAFE

            NOTE: A bolt override may not allow the weapon to be placed on SAFE

(3) Remove the magazine

(4) Lock the bolt to the rear

(5) Place the weapon on SAFE (if not already done)

 These videos and steps give you a great understanding and skills to keep your AR-15 ready and operable. 

John Boyette

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