AR-15 Feeding Problems Caused by Ammo
AR-15 ammo feeding problems can sometimes be traced to the ammunition itself, but a failure to feed does not automatically mean the ammunition is defective. Magazines, firearm condition, chambering, cartridge dimensions, bullet profile, and other mechanical factors can all contribute to a feeding malfunction.
A useful troubleshooting approach is to separate ammunition-related problems from firearm- or magazine-related problems. Before changing ammunition or attempting any repair, follow the firearm manufacturer’s instructions and basic firearm safety practices.
What Is an AR-15 Feeding Problem?
A feeding problem occurs when a cartridge does not properly move from the magazine into the chamber during the firearm’s feeding cycle. SAAMI defines a misfeed, or failure to feed, as a malfunction in which a cartridge fails to enter the chamber completely.
Not every malfunction that looks like a feeding problem has the same cause. For example, a cartridge may fail to leave the magazine correctly, may contact part of the firearm during feeding, or may not chamber completely.
That distinction matters because the ammunition may be only one part of the problem.
Can Ammo Cause AR-15 Feeding Problems?
Yes. Ammunition can contribute to feeding problems when individual cartridges are damaged, incorrectly configured for the firearm, contaminated, or otherwise outside the expected characteristics of ammunition intended for that firearm.
Potential ammunition-related contributors include:
- Damaged or deformed cartridge cases
- Deep dents or significant scratches
- Corrosion
- Damaged bullets
- Unusual or incompatible bullet profiles
- Incorrect cartridge designation
- Cartridges that have been repeatedly rechambered
- Ammunition exposed to water, fire, chemicals, or extreme conditions
- Individual defective cartridges
SAAMI recommends inspecting ammunition before use and specifically advises against chambering or firing cartridges showing physical damage such as corrosion, deep dents, or scratches. It also states that ammunition should chamber easily and that a cartridge requiring unusual force to close the action should not be fired.
1. Damaged or Deformed Cases
The cartridge case has to maintain the appropriate shape and dimensions for the firearm to feed and chamber it properly.
A visibly damaged case can interfere with normal feeding or chambering. Dents, severe scratches, corrosion, or other physical damage are reasons to remove a cartridge from use rather than trying to force it into the chamber.
Ammunition that has been repeatedly loaded and unloaded can also sustain physical damage. SAAMI notes that repeated rechambering can damage the case and primer, and that repeated rechambering can push the projectile deeper into the case.
For that reason, repeatedly cycling the same cartridge through an AR-15 is not a good way to troubleshoot a feeding issue.
2. Incorrect Ammunition or Chambering
One of the first things to verify when troubleshooting an AR-15 is that the ammunition matches the firearm’s chambering and the manufacturer’s instructions.
This is particularly important with .223 Remington and 5.56 ammunition.
SAAMI states that .223 Remington ammunition can be used in a firearm with a 5.56 military-specification chamber, subject to the manufacturer’s verification. It also warns that 5.56 ammunition should not be fired in a firearm marked .223 Remington because chamber and throat differences can create excessive pressure.
The barrel marking and firearm owner’s manual should therefore be checked before assuming that ammunition is compatible.
The headstamp is another useful identification point. SAAMI recommends confirming that the ammunition designation corresponds with the firearm’s chambering.
3. Bullet Profile Can Affect Feeding
The shape of the projectile can influence how a cartridge interacts with the feeding path.
Different 5.56 and .223 loads can use different bullet designs, including:
- Full metal jacket
- Open-tip projectiles
- Hollow-point designs
- Soft points
- Polymer-tip bullets
- Other specialized projectile profiles
A cartridge that has a different overall shape from another load may interact differently with a particular firearm or magazine.
This does not mean that one bullet style is inherently unreliable in AR-15 rifles. Rather, it means that individual firearm and magazine combinations can behave differently with different ammunition.
If one particular load repeatedly causes problems while another known-compatible load functions normally in the same firearm and magazine, the ammunition becomes one variable worth investigating.
4. Ammunition Dimensions Matter
Factory ammunition is manufactured to established dimensional and performance standards. SAAMI’s centerfire rifle standards include dimensional and performance characteristics for cartridges and rifle chambers and are intended to support safety, reliability, and interchangeability.
A cartridge that is damaged or otherwise outside expected dimensional characteristics can behave differently during feeding or chambering.
This is one reason forcing a questionable cartridge into the chamber is not an appropriate troubleshooting method.
If a cartridge does not appear to chamber normally, stop and determine why rather than applying additional force.
5. Repeatedly Loaded Ammunition Can Become a Problem
A cartridge that has been repeatedly loaded into a magazine and chambered can experience more handling than a cartridge fired directly from its original packaging.
SAAMI specifically warns that repeated rechambering can cause physical damage to ammunition. It also notes that repeated exposure to recoil can damage cartridges that remain in a firearm or magazine, particularly during training or similar use.
Look for obvious signs of damage before using ammunition that has been repeatedly cycled.
If there is any doubt about a cartridge’s condition, do not use it.
6. Corrosion, Contamination, and Environmental Exposure
Ammunition exposed to unfavorable conditions can develop problems that are not always obvious at first glance.
SAAMI recommends storing ammunition in a cool, dry location away from solvents, chemicals, heat sources, and open flames.
Ammunition that has been exposed to water, fire, or extreme conditions deserves additional caution. SAAMI notes that hidden damage can occur when ammunition is exposed to fire or water and has published specific guidance for ammunition exposed to those conditions.
Do not assume that ammunition is safe to fire simply because the outside appears normal after significant environmental exposure.
7. The Magazine May Be the Real Problem
A feeding malfunction that occurs with one magazine does not necessarily indicate an ammunition problem.
The magazine is responsible for presenting cartridges to the firearm in the appropriate position for feeding. A problem with the magazine can therefore produce symptoms that look like ammunition-related feeding failures.
For example, if the same ammunition works normally with one known-good magazine but repeatedly malfunctions with another, the magazine becomes an important variable to investigate.
This is why changing several variables at once can make troubleshooting more difficult.
8. The Firearm Itself Can Cause Feeding Problems
Ammunition is only one part of the feeding system.
Other possible contributors include:
- Magazine condition
- Firearm wear or damage
- Chamber condition
- Ammunition compatibility
- Bolt or action-related problems
- Improper modifications
- Debris or contamination
- Other mechanical issues
SAAMI advises that firearm repairs should not be attempted by unqualified personnel and recommends contacting the firearm manufacturer, an authorized repair facility, or a qualified gunsmith when mechanical problems require attention.
That is particularly important when a feeding problem is persistent rather than isolated to a particular cartridge.
How to Tell if Ammo Is Causing the Problem
The most useful approach is to change one variable at a time.
Suppose an AR-15 has a feeding problem with one particular ammunition load.
Instead of immediately changing ammunition, magazines, and other variables simultaneously, document what happened and look for a pattern.
A simple diagnostic comparison can look like this:
| Observation | What it may indicate |
|---|---|
| One visibly damaged cartridge fails to feed | Cartridge condition may be relevant |
| Several loads malfunction in the same firearm | Look beyond ammunition |
| One ammunition load repeatedly malfunctions while another compatible load functions normally | Ammunition becomes a variable worth investigating |
| Problem follows one magazine | Magazine becomes a stronger suspect |
| Problem occurs regardless of ammunition or magazine | Firearm or chamber-related factors deserve attention |
| Ammunition does not match the firearm’s specified chambering | Stop and verify compatibility |
This is not a definitive diagnosis. It is a way to isolate variables without assuming the cause prematurely.
What Should You Check on the Ammunition?
Before using ammunition in an AR-15, inspect it for obvious problems.
Look for:
- Corrosion
- Deep dents
- Significant scratches
- Damaged or deformed bullets
- Unusual cartridge appearance
- Contamination
- Signs of severe environmental exposure
- Incorrect cartridge designation
SAAMI recommends inspecting ammunition before use and disposing of cartridges that show physical damage according to applicable federal, state, and local requirements.
Do not try to make a questionable cartridge usable by forcing it into the chamber.
What If One Round Will Not Chamber?
Do not force the action closed on a cartridge that does not chamber normally.
SAAMI specifically states that ammunition should chamber easily and that a cartridge requiring abnormal force to close the bolt or breech should never be fired.
If a cartridge does not chamber:
- Keep the firearm pointed in a safe direction.
- Follow the firearm manufacturer’s procedures for handling the malfunction.
- Do not force the cartridge into battery.
- Remove the questionable ammunition from use.
- Inspect the ammunition for obvious damage when it is safe to do so.
- If the problem persists, consult the firearm manufacturer or a qualified professional.
If the firearm fails to fire, SAAMI recommends keeping the muzzle pointed in a safe direction, waiting several seconds, and following its misfire-handling guidance before removing the ammunition.
Why You Shouldn’t Immediately Blame the Ammo
It is tempting to assume that a feeding malfunction means the ammunition is bad, especially when a particular cartridge appears to be involved.
But one malfunction does not establish a cause.
Ammunition, magazine, firearm, chambering, and environmental conditions can interact. A useful troubleshooting process therefore looks for repeatable patterns rather than relying on a single malfunction.
For example, if the same ammunition repeatedly causes problems while a different, manufacturer-compatible load consistently functions normally in the same firearm and magazine, ammunition deserves closer attention.
If several different loads produce the same malfunction, ammunition alone becomes a less complete explanation.
When to Stop Using the Ammunition
Stop using ammunition when you identify obvious physical damage or when its compatibility with the firearm cannot be established.
Particular warning signs include:
- Deep dents
- Severe scratches
- Corrosion
- A damaged projectile
- Incorrect cartridge designation
- A cartridge that does not chamber normally
- Ammunition exposed to fire or severe environmental conditions
- Repeated malfunctions associated with a particular lot or load
When in doubt, contact the ammunition manufacturer for guidance rather than experimenting with questionable cartridges.
Common Mistakes When Troubleshooting Feeding Problems
Changing Too Many Variables at Once
Changing ammunition, magazines, and other components simultaneously makes it difficult to determine what changed the outcome.
Forcing a Cartridge Into the Chamber
A cartridge that requires unusual force should not be forced into battery. SAAMI specifically warns against firing ammunition that requires abnormal force to close the action.
Continuing to Use Damaged Ammunition
A damaged cartridge should not be treated as a test round. Remove it from use and follow appropriate disposal guidance.
Assuming Every Malfunction Is an Ammo Problem
A feeding malfunction can originate elsewhere in the firearm or magazine system.
Ignoring the Firearm Manual
The manufacturer’s manual provides the firearm-specific information needed to verify chambering, ammunition compatibility, and safe operation. SAAMI also recommends consulting the manufacturer’s documentation for firearm-specific guidance.
AR-15 Ammo Feeding Problems: A Practical Takeaway
AR-15 ammo feeding problems can be caused by ammunition, but ammunition is only one possible source of a feeding malfunction.
Start with the basics: verify the correct cartridge, inspect the ammunition, avoid damaged or questionable rounds, and pay attention to whether the problem consistently follows a particular ammunition load or magazine.
Most importantly, never force a cartridge that does not chamber normally. If the malfunction continues across different known-compatible ammunition or cannot be safely isolated, stop using the firearm and consult the manufacturer or a qualified gunsmith.
A methodical approach is safer and more useful than assuming the ammunition is responsible after a single malfunction.