Home AR-15 Quick Tip: Top 3 Causes of AR-15 Malfunctions

Quick Tip: Top 3 Causes of AR-15 Malfunctions

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The AR-15 has become America’s Favorite Rifle, and with that distinction comes a lot of calls to our Gun Techs about problems with AR-15 operation. Fortunately, one of those intrepid techs, Caleb Savant, is here tell us about what causes the three most common AR-15 malfunctions. These problems are most common on homebuilt ARs, though they sometimes crop up on factory guns, too. First problem: Gas block misalignment. When the hole in the gas block is not lined up with the gas port in the barrel, gas flow is disrupted, leading to failure to feed, failure to extract, or failure to eject. (See our earlier Quick Tip video “AR-15 Gas Block Alignment” for more info.) Second problem: Wrong buffer weight and/or spring. This can lead to “over-gassing” (too much gas flow) or “under-gassing” (not enough). Even worse, sometimes those two conditions look the same! Third problem: Hammer spring not installed correctly. Put it in backwards, and you get light hammer strikes that fail to detonate the primer. Worse yet, the firing pin often gets blamed for this. Self-contained, drop-in trigger units don’t have this problem. But if you’re installing a mil-spec trigger, take extra care to get that hammer spring oriented correctly.

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49 COMMENTS

  1. Good video. Also if you are Handloading for an AR, the CASE LENGTH is Critical. Too long and the fired rounds will "Stovepipe" and jam. Easy fix…keep the brass trimmed to OAL recommended. AR chambers cause a lot of stretching of the brass cases.

  2. Caleb reminds me of a ‘50’s era insurance salesman…RESPECTFULLY! Dude knows his AR’s,…firearms. Myself, I run H2 buffers exclusively on every AR carbine I own, thanks Patrick Sweeney (THE AR guru)

  3. That cutaway AR15 looks very interesting and well done. I would really like to see a detailed video of it in motion. I searched your channel but didn't find one. Great videos altogether. Thank you.

  4. Pro tip: If you have an A2 gas block/front site and want a low profile gas block that will function as well as the A2 than don't buy a new gas block. Cut down and grind the A2 and pin it back in place. Save money and keep it reliable.

  5. Another cause of malfunction from my experience is the gas key above the bolt carrier. When this is loose after firing and not properly staked in will cause short stroking or no cycling of the bolt. When you experience this, check the gas key along with the 2 screws holding it in. In that case you will have to replace the bolt carrier because the screw threads have exceeded the proper amount of threads adequately by specs for the screws to hold in the gas key and staked in. The symptoms are simple. First is the staked screws have walked out from being solidly staked and when the gas key wobbles and it's loose. Replace the bolt carrier as a complete system. Barrels on the M16A2, A4, and M4s are fine, reason is the diameter of the gas ports at the sight tower are heavily cut larger to be designed to be over gassed. The gas ports on current military barrels are larger than the original M16A1 as the A2 it has replaced and carried on into the M4 and A4 models. It may have altered the lock time but not that much affect extraction, ejection, and cycle. In fact it has caused better cycling with higher pressures that the 3 gas rings have become too minor of an issue to their function as to be there to regulate gas and dwell time to extract, cycle, extract, eject and feed. The 3 rings by design are part of the system in order for the weapon to function.

  6. My first build was initially short stroking. Traced it down to gas leakage from between the bolt carrier and gas key. A coat of Copper Seal gasket treatment in between the parts fixed it.

  7. Another big failure… Missing parts. Due to the panics of 2020.
    For example the BCG I want for my build is out of stock. On the plus side the rest of my parts were in stock and ordered. Brownells has my BRN10 stripped lower on the way to my FFL and everything else sent to me. My first gun of 2021!

  8. I used a straitedge to determine the center of both the gas port and "gas hole" of the gas block…lined up the pencil marks then checked for alignment with a section of fish tank aerator hose attached at the rear of the gas tube…blowing in to it and lustening for the sound of air escaping into the barrel…can't remember where I picked this tip up from…but it works…

  9. On my own builds I've had 2 different barrels from 2 different makers (not top of the line but reputable makers) with sharp feed ramps on the barrel extensions that literally shaved bits of brass off the cases that led to chambering problems. Polish those feed ramps. Hell of a lot easier to do before the barrel is mounted

  10. If you're not fighting the hammer spring pressure to get the pin installed is a pretty good indication something is wrong. And I guess most mass production barrels are drilled oversized so they won't get consumer complaints about feed functions. Ehh.. it's only Thursday, I could be wrong.

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