Help! My AR Won’t Cycle – AR10 and AR15 Troubleshooting

Help! My AR Won’t Cycle – AR10 and AR15 Troubleshooting Here is a AR troubleshooting guide you can share when someone’s AR won’t cycle… or if you weren’t really “asking […]

Hyskore Track and Elevate shooting rest with WMD Guns Beast AR15Help! My AR Won’t Cycle – AR10 and AR15 Troubleshooting

Here is a AR troubleshooting guide you can share when someone’s AR won’t cycle… or if you weren’t really “asking for a friend”, when your AR15 or AR10 won’t cycle.
By “AR won’t cycle” I mean that the AR chambers a round and fires, but does not complete the cycle of:
  • ejecting the spent case
  • loading a new round into the chamber
  • locking the bolt
  • resetting the trigger

Safety first!

Before you do ANYTHING else, make sure the AR is unloaded and no round is in the chamber. Put ALL ammo in another room. That may sound silly, but people are creatures of habit. Every year lots of otherwise intelligent people chamber a round out of habit while working on their guns and cause a negligent discharge because they either didn’t realize they chambered a round, or they forgot. Don’t be like those people.

Step 1 – Check the easiest stuff first

Don’t tear your AR apart and start filing metal, cutting springs, etc. until you have positively identified the root cause of the problem. Chances are very high that no metal will need to be shaved, filed or cut. If you truly had the skill to make those modifications, then you wouldn’t be reading this article.

Easy things to check:

  • That’s just nasty!

    Is the magazine fully inserted and locked in place? If not, figure out why. Try different magazines.

  • Is it your ammo? Out of spec ammo may not chamber, or may not have enough energy to cycle the action. Try different brands and/or lots/batches of ammo.
  • Will the AR cycle manually (using the charging handle)? Does it cycle fully, or stop before the bolt catch is engaged?
    • If it cycles fully and without binding, them move on
    • If it doesn’t cycle fully, you have to figure out what is stopping it.
      • Are both takedown pins fully inserted?
      • Is the correct length buffer spring in the buffer tube?
      • Is the correct length buffer in the buffer tube?
      • Is there anything else in the buffer tube keeping the spring from seating at the aft of the tube?
  • Is the AR clean? Too much carbon buildup can make an AR stop functioning. Get a good cleaning kit and clean it all. Remove the bolt, strip and clean it, clean the inside of the upper and lower receivers. Don’t be shy.
  • Is your AR properly lubed? You don’t perform well when you are run dry. Neither does your AR. Apply some gun oil to the contact areas on the BCG and on the bolt rings.

JP Enterprises Armageddon Gear Revolution Trigger close upStep 2 – If none of those easy things fixed it, time to dig a bit deeper

  • Loosey Goosey? Look for any loose parts like:
    • gas block
    • gas tube
    • gas key
    • barrel nut
    • trigger pins
    • castle nut securing the buffer tube
  • Missing or worn parts?
  • Reduced gas flow? 
    JP Enterprises JPGS-5BC Adjustable Gas System for AR15 AR10 Review - install gas tube

    Josejuan lining up the gas tube to install the roll pin

    Keep in mind that not all ARs have gas systems. For example, Pistol Caliber Carbines are usually blowback operated.

    • Is your gas block aligned with the gas port in the top of the barrel? The easiest way I know to confirm this is to loosen gas block, close the bolt and blow compressed air into barrel (I like to use an air compressor). Wiggle the gas block around until you hear the most airflow, then tighten gas block in that position. Don’t forget that the gas block is NOT supposed to touch the shoulder just aft. There should be a gap just wide enough for the front handguard mount (for the old style delta ring, non-free floated handguards).
    • If you have an adjustable gas block, open it a few turns and see if that helps
    • Is your gas tube obstructed?
    • Is gas tube mating with gas key correctly?
    • Is gas key tight and sealed to bolt (no air gaps)
  • Buffer Tube obstruction? Verify there isn’t anything in the buffer tube that shouldn’t be.
  • Correct spring? Verify you have the right buffer spring. If you aren’t sure, look it up. If you feel the temptation to cut your spring… don’t.
  • installing KynSHOT buffer in ar15

    Correct buffer? Make sure you have the correct buffer for your gas system. If your AR is short stroking, maybe try a lighter buffer.

What else?

What else have you seen that kept an AR from running properly. Leave your comments and maybe we’ll add your suggestions to the list.
Like this, which we found in a FB discussion comment:

About Jeff

Jeff is the Editor in Chief of Gear Report and a National Shooting Sports Foundation Media member. He reports on the outdoor industry, reviews gear for camping, hiking, shooting, hunting, paddling, backpacking and other active pursuits. A USAF veteran, Jeff earned a MBA in Marketing and Health Services. He specializes in consultative selling and internet marketing. As the VP of BD & Marketing, Jeff provides sales and marketing leadership to MGECOM, Inc. and helps acquire new clients in need of solutions for online merchants in need of Affiliate Marketing program management. Jeff founded and manages Cress Sales & Marketing LLC, offering online sales and marketing consulting and services to online merchants and service providers.