Common AR-15 Problems

By Bob Campbell

The AR-15 rifle is a great rifle—America’s rifle—and a system with a well-deserved reputation for reliability. And that was not always so, and it is possible to ruin any design with poor maintenance and improper loads.

The first rule is good lubrication.

The use of the wrong type of powder by the arsenals caused quite a few problems in Vietnam, then the Army finally caught up with the problem.

The AR-15 is revered as a low-maintenance rifle and that is true when compared to what came before it. The black powder rifles once used by the Army had to be cleaned after every battle or every shot, otherwise black powder residue quickly rusted.

Corrosive salts in primed ammunition meant much the same for the M1 Garand and the bolt guns it replaced. The M1 carbine was the first true, low-maintenance rifle adopted by the U.S. Army and, within its limitations, the carbine did a great job. The original AR-15 with the proper ammunition was very reliable and did not require as much maintenance as the previous M14, and it does require cleaning and lubrication, and occasionally parts replacement.

The AR 15 is popular, easy to use well and accurate. To keep it rolling, follow a few simple rules.

  • Keep the rifle clean to prevent eccentric wear.
  • Clean it as if your life depends on it. For some, the rifle is an emergency firearm, and your life may well depend on it. For many, the AR-15 is a hunting rifle. A tie-up ruins a hunt or an important rifle match.
  • The AR-15 operating mechanism, including the trigger group, bolt and chamber, must be cleaned and made free of powder ash and debris. That cleaning cannot be accomplished by simply spraying with an aerosol. You must remove the bolt and bolt carrier and wipe them with an oily rag.

Basic Cleaning Steps

  1. Dissemble the bolt carrier group.
  2. Carefully clean it.
    I formerly used an old toothbrush, although now I use purpose-designed cleaning tools.
  3. Scrub with a good powder solvent.
  4. Clean the rifle again.
    Be certain to clean the area between the bolt and the barrel in the locking lugs where carbon buildup is often significant. I use specialized gun-cleaning picks to make sure the rifle is clear of carbon deposits.

This AR-15 bolt is awash with lubricant before a trip to the range.

These carrier keys are well staked. Note the solid indent around the carrier key to prevent movement.

This is an area of concern for the AR-15 rifle. Get a brush in there to clean it.

Clean the area around the locking lugs and chamber thoroughly.

While the rifle may function (and function well) with a certain amount of carbon buildup, there is a difference between normal and eccentric wear. Normal wear results in a rifle that will last for many thousands of rounds. Eccentric wear, or uneven wear, begins cutting into the metal much quicker. If you have experienced a malfunction, then clean the rifle, doing a bang-up job. Next, look at the extractor spring, which may need to be replaced.

Poor Accuracy

Another problem is poor accuracy, and while not strictly a malfunction, the rifle is not operating at its peak. This is especially true if it once demonstrated good accuracy. The problem is almost always a fouled bore. I have yet to see a shot-out AR-15 barrel, and have seen ruined barrels.

A muzzle brake reduces recoil and protects the muzzle.

Clean with a good bore solvent, using wet and dry cloths, a good bore bush and plenty of elbow grease. Once you have cleaned the action and barrel, the rifle’s problem may be fixed. If not, you need to look for the real problem. A damaged muzzle may result in poor accuracy, particularly in a rifle with no muzzle brake. A good gunsmith can re-crown the barrel and restore accuracy. Poor-quality ammunition also results in bad accuracy.

Ammunition

A staple of the gun writer is to fire a magazine of mixed ammunition to confirm reliability. That is OK as far as it goes, as long as you remember the loadings and their position in the magazine if you do have a malfunction. And mixing quantities of ammunition is not always a good idea.

There is nothing better than ripping open a newly arrived carton of ammunition. Hornady ammunition will never give you a moment’s problem. It burns clean and provides excellent accuracy.

A staple of the gun writer is to fire a magazine of mixed ammunition to confirm reliability. That is OK as far as it goes, as long as you remember the loadings and their position in the magazine if you do have a malfunction. And mixing quantities of ammunition is not always a good idea.

  • Steel cases often are coated with a polymer finish, which gets hot and melt a bit on firing.
  • Steel-cased rounds seem to zip right through that mess, although brass does not always feed through a polymer-lined chamber.
  • Stick with one loading or the other for reliability.

Lubrication

Keep the gun lubricated. In the case of a rifle kept for defense or pest and predator control, a little lubricant is fine. You probably will only fire a few rounds.

  • If you are going for a long practice session at the range, keep the rifle wet.
  • If you fire 100 rounds or more, keep lubricating the bolt and cycling the action before you continue firing. That goes a long way toward maintaining function.

The Trigger Group

Another concern is the trigger group. The trigger sometimes becomes inconsistent, with a differing amount of force needed to break the sear. That is because the action has become dirty and powder or other grit is in the trigger action. I have seldom seen issues with a quality AR-15 and good ammunition; when I have, the culprit usually was poor lubrication (parts guns with improperly staked carrier keys and other problems are a headache).

Poor-Quality Magazines

Another source of problems is poor-quality magazines. Many magazines work just fine when new although if dropped, or even handled roughly (such as slamming into the magazine well), they warp, crack or bend. The result is poor feeding. Trash an offending magazine. Your life is worth more than the price of a new PMAG.

Gas Rings

Gas rings are simple to test and replace.

  • If you extend the bolt from the carrier group and place it on a desk or table, it should support the weight of the carrier group.
  • If not, change the gas rings.

With proper lubrication, cleaning, good-quality magazines and using proven ammunition, the AR-15 rifle is reliable.

For fun shooting, keep the AR-15 lubed and maintained.

When problems occur, the concerns discussed are responsible for the lion’s share of difficulty.