M&P 15X, nearly flawless history, was a single shot rifle today?

[brettskywalker]

I bought the rifle new over 5 years ago, take very good care of it, clean throughly & keep it well lubed. My last range trip I shot 200 rounds of 62 grain green tip & didn't have a hint of a problem. The round count of the gun is about 6000 rounds,+ or - a few. Where should I look 1st? The gun would fire & not eject, but several times it did eject the case & then light strike? It was almost back & forth, no case ejection, drop the mag, pull the CH & it WOULD eject the spent case. Put the mag back in, load a round, fire, case ejected, pull the trigger, & hear a faint click & no bang. Wait 15 seconds, drop the mag, eject the round, looked at the primer & it had been struck. Put the mag in & manually worked the CH & it would pull a round out every time. Help please

 

[2hawk]

Loose gas key? Dirty chamber? Broken bolt? Obviously I am just guessing, but I would say strip and inspect your BCG carefully, and give the the chamber a real good scrub.


HTH

 

[MichiganScott]

Any changes since last time?

Do you use long pipe cleaners to clean the gas tube?

Detail strip and clean and lube in accordance to manual.

 

[AR-Getsome]

Is the fired casing still in the chamber? If it is, your extractor may be worn. It may be possible the worn extractor may not be seating the round fully onto the bolt causing the light strike. My buddy had a similar issue and we changed the extractor and all was well after that. I'm no expert just my thoughts.

 

[brettskywalker]

Damn, I was just practicing my Google - fu & came across an army malfunction checklist for all types of failures. One of them listed a possible cause from damaged chamber surface & the corrective action to take- REPLACE THE COMPLETE BARREL. This worries me because during my last cleaning I may have been using excessive force when using the chamber brush & it dropped down maybe a 1/4 inch further than I have had a chamber brush go & came to a stop like it hit a wall, or side of the chamber. This has never happened before & I didn't like the way it felt. What kind of imperfections in the chamber would constitute the need for a new barrel? Is a scratch ok? I haven't taken the rifle out since I got home, cleaned my edc pistol 1st, then started researching. Also, my extractor o ring is a little swollen & I can push down on the extractor near the pin & push it out with my thumbnail, I don't think it's ever been that easy. I am going to order a bolt repair kit tomorrow that will come with an extractor, spring, insert, o ring, as well as ejector & spring. How do I tell if my buffer spring shot?

 

[brettskywalker]

Yes, fired casings were still in the chamber, but it did manage to eject 2 fired casings out of the gun. Next trigger pull resulted in a light strike. Every failure was able to be cleared by dropping the mag & pulling the CH. In both cases, whether it was a fte or light strike, pulling the CH easily cleared whatever was left in the chamber. I'm going to clean it & take a closer look tomorrow. After I get the replacement extractor & ejector parts I'm hoping it will be gtg

 

[AR-Getsome]

Yes, fired casings were still in the chamber, but it did manage to eject 2 fired casings out of the gun. Next trigger pull resulted in a light strike. Every failure was able to be cleared by dropping the mag & pulling the CH. In both cases, whether it was a fte or light strike, pulling the CH easily cleared whatever was left in the chamber. I'm going to clean it & take a closer look tomorrow. After I get the replacement extractor & ejector parts I'm hoping it will be gtg

Pretty much what my friends rifle was doing before the extractor change. As far as the buffer spring goes,I haven't changed one out yet. Someone here like Japes or rastoff can answer that question. They must be out at the range not to answer here yet.

 

[brettskywalker]

Much to my surprise my local gun shop has new extractor components in stock. I will be picking them up on my lunch break. Probably won't get to live fire test until the weekend.

 

[brettskywalker]

Well I just picked up a replacement extractor, extractor spring with insert, but no one ring. The person at the counter had no idea what an extractor, spring with insert or o ring was. He had to find the head gunsmith to show him the parts. Gunsmith came out with the extractor & spring w/insert &I asked him if they have the o ring that surrounds the spring. His reply " I've never heard or seen 1 before & I ve been a gunsmith for 30+ years." Wow! I told told I bought my rifle new from their shop 5-6 years ago & it came stock with my rifle. Crazy how many people work at gun shops that have very little knowledge of the guns they sell the most of.

 

[rtquig]

I have seen some extractors that don't use the O ring.

 

[AR-Getsome]

^^^^^^ correct. My dpms rifles do not use the o-ring. My Bushmaster does use it. I'm not entirely sure the reason why some use it and some don't. A gunsmith that has no idea about parts on firearms willl never work on my firearms, especially if I know more than he does.

 

[brettskywalker]

That's weird, I was just reading up on the whole o ring thing. & it is true that a lot of bolts don't have them & just use the insert. There WAS only 1 guy there that I would trust to work on any of firearms & he is no longer there. I prefer to do anything that sounds simple & i have the tools to do myself.

 

[Rastoff]

I seriously doubt this is an extractor issue. If it were, you would be getting a double feed (Type III malfunction) when the round fired, but failed to extract. The bolt would still cycle and just leave the spent casing in the chamber. Then it would try to strip the next round off the mag and it would get stuck because it couldn't feed into the chamber. It would look like this:

However, what you're describing sounds like the bolt is not cycling. This is more commonly caused by the gas system failing. One thing that could cause the gas system to fail is the bolt gas rings:

At the back of the bolt are three rings. They are what make a good seal with the bolt and the bolt carrier. If the openings of those rings are all lined up, they will let the gas by without operating the bolt. Or, if one or more of those rings is damaged, it would also let the gas by without operating the bolt. It might still work intermittently, but certainly wouldn't be reliable.

The most common cause of the light strikes will be a dirty firing pin channel. The hole the firing pin sits in is probably the most over looked aspect of cleaning any gun. I see this kind of malfunction a lot in the sporting shotgun world. With a small scribe or some other small pointy thing, gently scrape the inside of the firing pin hole. Check to see if much carbon or dirt comes out. Then check the shoulder of the firing pin itself. Look for any build up. If you find any, that will certainly cause a light strike.

The reason they suggest replacing the barrel is in case the gas port in the barrel is damaged or clogged. It's easier to just throw another upper on the gun than to clean the gas port. Remember, the AR was intended to be fixed in the field. Therefore, it's easier to just throw another upper on it (i.e. replace the barrel) than to fix it down to the level of the gas port.

These are just some ideas I had when I read the OP. Take them as you found them.


This is a pretty good description of how the gas system works.
How the AR 15 Bolt Carrier Group Works - YouTube

 

[brettskywalker]

I changed out the extractor & spring with insert & also put the old o ring back on. I will say it took about 5x as much thumb strength to push the extractor in enough to align the pin through the holes. I took it off, & put the original setup back on with very little effort. Now that I think about, for safety, anytime I pull the trigger, hear a click followed by SILENCE, the 1st thing I do is count to 5,drop the mag. Now I confused myself & cant remember if any live rounds or cases fell out with the mag. The idea of it not cycling at all has also crossed my mind & i will need to look into it.

 

[WR Moore]

OP- have you done the gas ring test? Take the BCG, remove the firing pin and cam pin. Holding the BCG by the bolt, turn it vertical, carrier down. If the carrier falls off the bolt, replace the gas rings. Do check the gas ring gap alignment.

Note: I've seen rifles that will fail this test that function flawlessly.

The light strike on rounds that chamber after a round ejects shows the BCG isn't going fully into battery. The BCG isn't moving at full speed during its cycle, it isn't getting all the gas it needs.

Do check the gas key, possibly use an aresol cleaner in the gas tube. Make sure the barrel is dry before attempting to fire.

BTW-who made the green tip ammo? Not all is created equal. More to the point: exactly what ammo are you shooting now? Has it been reliable in the past.

 

[2hawk]

Brett, don't worry too much about the gas ring gap alignment- Larry Vickers has run guns with just ONE ring to disprove what he characterizes as an old wives tale (my words, not his).* The test above IS a good test to see if the gas rings are worn.

But do check all components, and particularly the gas key. Not all mfr's do a good job on staking the bolts. Also, next time you're shooting, do a lockback test- either with just one round loaded in the mag, or by pushing the bottom of the bolt release when firing, to make sure your bolt is actually traveling back far enough to cycle correctly.

Lots of troubleshooting tips in the stickies over on arf, just stay out of GD.

*From another thread, another time and place: "No expert.. but prove it to yourself... Fire with only one gas ring. It will run. They work like piston rings... once there [sp] inside the carrier, the rings are squeezed tight closing the gap... myth that has been dispelled by Many Top trainers like Pat Roger's, Jeff Gonzale's, Larry Vickers, Ken Hackathorn, Louis Awerbuck and on and on.."

HTH

 

[brettskywalker]

Today I haven't had a chance to touch the rifle. I actually for the first time ever check the gas key screws for tightness, prior to my last trip, they didnt budge. I still run the factory ar 15 cut bolt that came with the gun, stock buffer spring, I have switched to an H1 weight buffer & it ran smoother without issue. The ammo I've been using is 62 grain 556 American eagle green tips. I lucked out & received a bunch of coupons from Dicks & was able to use all of them in addition to the store sale, so I got an excellent deal. The ammo has been shooting pretty accurate for me too. My gas rings are not stock & were replaced about 6-700 rounds ago, are in good shape & passes gas ring test. What's the lifespan of an EJECTOR & ejector spring?

 

[2hawk]

Depends on what you're shooting, and how much. I've put thousands of rounds through a couple of my guns with no hard parts changes. I did upgrade all my EXTRACTORS with Bravo Co. springs and O rings, but not because I had any problems.

Just an aside: One other piece of mis information I found in this thread: NEVER put anything down your gas tube. You have a 50KPSI blast of hot gases though it every time you fire the gun to keep it clean, and you're more likely to cause a problem by trying to stuff something in it.

BTW, did you carefully inspect the chamber?

 

[WR Moore]

I did upgrade all my ejectors with Bravo Co. springs and O rings, but not because I had any problems.

I've seen o-rings and d-rings on EXTRACTORS, never on ejectors.

The ejector isn't the issue here, if the shell doesn't leave the chamber, the ejector doesn't function. Not to be insulting, but the ejector is the plunger in the bolt face.

What you appear to have here is short stroking of the BCG, if it's moving at all. If you have a...whatever they call a video camera these days...you might try recording the bolt movement during firing. Slow motion may show you things.

The one round in the mag test is a very good idea. Even if the extractor/ejector are causing issues, the bolt should lock back if the BCG is moving properly.

You'd have to take a chunk out of the chamber wall to impair extraction & ejection.

The aresol cleaner in the gas tube is a flow check. It's not likely that modern ammo will clog the gas tube, but it's an easy way to check. If you watch the bore and don't see spray, you've got an issue somewhere in the tube/sight forging/gas port.

 

[2hawk]

I've seen o-rings and d-rings on EXTRACTORS, never on ejectors.

...
The aresol cleaner in the gas tube is a flow check. It's not likely that modern ammo will clog the gas tube, but it's an easy way to check. If you watch the bore and don't see spray, you've got an issue somewhere in the tube/sight forging/gas port.

So sorry, WR- brainfart after a long hard day. Extractor is what I meant, as you easily surmised... and good tip on the gas tube check.