AR15 malfunction... kinda of

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Thread: AR15 malfunction... kinda of

  1. #1
    Distinguished Member Array RKM's Avatar
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    AR15 malfunction... kinda of

    Experienced my first malfunction in my M&P15 in a few thousand rounds. It was actually more like a misfire.

    Was shooting 100% and suddenly the recoil felt slightly different for one or two rounds half way through the mag, almost similar to the bolt catching. I actually checked the ejection port once or twice to see if I was empty. But I wasn't and kept shooting. But those rounds cycled and fired with no issue. Then after those two I felt a click. I checked for a double feed or any sort of malfunction and didn't see anything wrong. The hammer felt like it dropped. It wasn't mushy. I checked the ejection port and the BCG looked to be fully seated into battery at a quick glance. I extracted a fresh chambered round from the chamber. Didn't look like it had a primer hit at all. Not even the soft dimple from being chambered. But I didn't study it closely. I put that round back in the mag, chambered it manually and fired off the rest of the mag and another mag without any issue.

    I pulled the BCG out and made sure the firing pin moved freely, which it does. It was slightly dirty and grimmy so the firing pin would ever so slightly stick forward or rearward. It didn't move freely from gravity alone by tilting the BCG up or down. But with little pressure, and I mean barely touching it with my finger it would move. So I don't think that was the problem. Everything in the lower and the hammer looked ok. Hammer drops properly.

    FWIW, I'm using an M&P15X, factory 1:9 twist barrel, a complete BCM M16 BCG, an H buffer with the factory spring. The lower is 100% factory. I was using a GI mag by Okay Industries with a Magpul follower and Federal XM193 5.56 ammo. None of this stuff has ever given me problems before.

    It literally just felt like a dead round, but there was what looked to be no primer hit at all. Not even a light strike. I'm wondering if the round didn't chamber all the way, allowing the hammer to drop but not actually hit the firing pin (not sure if that's possible). In which case, what would be the solution? I would think if the chamber was too dirty I'd get rounds not extracting from the chamber. I just can't think of what could cause this problem other that a hard, defective primer, but like I said, it didn't even look like the firing pij ever even touched it and it fired off perfectly on the second attempt.

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  3. #2
    VIP Member Array glockman10mm's Avatar
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    If it fired with no issues that one and others, its probably just a case where it didnt seat fully due to retarded cycling of the action from the former under pressure rounds.

    I would pull the pin and inspect to make sure the tip isnt damaged for peace of mind.
    Ignorance is a long way from stupid, but left unchecked, can get there real fast.

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    Member Array the6shooter's Avatar
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    If you still have the round, check and see if the primer was pressed too deep in the case. I have came across some cheap ammo (russian) and have found a round or 2 like that.
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    For future reference, if a round doesn't feel right, and the recoil feels off, be sure to check the barrel for a squib load, to make sure it isn't obstructed, before you start shooting again.

    Did you check the OAL of the round, compared to the other ones?
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    Distinguished Member Array RKM's Avatar
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    Glockman: Are you referring to bolt bounce or the action cycling to quickly or too slowly? Would an H2 buffer maybe solve this? I know the M&P barrels are over gassed which is why I went to an H buffer an M16 BCG in the first place. The firing pin is in perfect shape. I had a firing pin break in my AK. I was having similar problems but they were much more consistent. I'd get a click and then extract the round and try again and bang, then maybe fire a few rounds, then click again. Ended up the firing pin broke, literally into two pieces. But that's not the case here. Just pulled the firing pin from the bolt and it's perfect.

    Shooter: I never think to check these things.... I don't have the case any more. I'm not sure whether or not the primer was pressed too deep into the case. At at quick glance it didn't appear anything was wrong with it. I only looked at it after the click. After it went bang it ejected into the pile of spent brass and I couldn't tell which one it was if I trid. I just put it back in the mag and kept shooting and it functioned flawlessly from there on out. And I try to avoid cheap ammo. It was Federal XM193. Not saying it can't have any issues, but it's not cheap stuff.

    buckeye: I know what you mean. I've done this a few times when handgun rounds, something would feel weird and I'd tear it down and check the barrel. However in this case the recoil that felt a bit strange didn't really feel off enough to alarm me, just enough to notice. I should have checked anyway. I did not check the OAL of the round when I pulled it from the chamber. Again, I never think to check this stuff. I'm still learning. I've only been seriously shooting fro a few years. Though at a quick glance when I held the round I think I remember still seeing the crimping on the bullet, so it wasn't set-back, if that's what you're referring to.

    If this was an ammo problem, I'm not too concerned. Or if it's an easy fix, or something blatantly obvious with the firearm or magazine, it's not a big deal. I just hate when my firearm malfunctions and I can't figure out why. I have to remember to check these things you guys mentioned if it ever happens again. The gun has been 100% reliable until today and it's been a few thousand rounds. I don't have the privilege of saying it's been 100% reliable anymore

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    Member Array garwha's Avatar
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    The two most usual trouble spots are a dry BCG, and a dirty chamber. I clean my chamber after each shoot, and at least oil the BCM through the gas ports on the BCM, and a little lub on the bolt rails. If you are shooting XM193 it's most likely a dry BCG though.

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    "Glockman: Are you referring to bolt bounce or the action cycling to quickly or too slowly?"

    You had mentioned the 2 rounds before not sounding or feeling right, so I was referring to the cycling velocity, which may have slowed just enough to strip off the next round and feed it, but not have enough velocity on return to fully seat the bolt, allowing just enough play to allow the hammer to fall, but cause the round to be pushed instead of detonated.
    Ignorance is a long way from stupid, but left unchecked, can get there real fast.

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    Quote Originally Posted by glockman10mm View Post
    "Glockman: Are you referring to bolt bounce or the action cycling to quickly or too slowly?"

    You had mentioned the 2 rounds before not sounding or feeling right, so I was referring to the cycling velocity, which may have slowed just enough to strip off the next round and feed it, but not have enough velocity on return to fully seat the bolt, allowing just enough play to allow the hammer to fall, but cause the round to be pushed instead of detonated.
    Ok, this is what I was thinking was possibly the problem that I made in my first post. It makes more sense the the way you explain it rather than they way I explained it. So an H2 buffer would likely make the problem worse. Do you think this is more a case of a weaker than normal round or the H buffer an M16 BCG I'm running causing it to cycle to slow? It's been nothing but reliable until today.

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    VIP Member Array dukalmighty's Avatar
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    Quote Originally Posted by buckeye .45 View Post
    For future reference, if a round doesn't feel right, and the recoil feels off, be sure to check the barrel for a squib load, to make sure it isn't obstructed, before you start shooting again.

    Did you check the OAL of the round, compared to the other ones?
    Good way to blow your gun up,I Saw an M16A1 upper receiver pretty much explode after firing a round behind a squib after the range officer cleared a guys malfunction,but never checked the barrel
    It sounds to me as if you had some ammo that was undercharged but had enough powder to cycle the action,In the future anytime you have a firearm that sounds different,lighter recoil,the slide wasn't cycled,stop shooting clear the gun of ammo,and check for a bullet lodged in the barrel
    "Outside of the killings, Washington has one of the lowest crime rates in the country,"
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  11. #10
    Distinguished Member Array RKM's Avatar
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    Quote Originally Posted by garwha View Post
    The two most usual trouble spots are a dry BCG, and a dirty chamber. I clean my chamber after each shoot, and at least oil the BCM through the gas ports on the BCM, and a little lub on the bolt rails. If you are shooting XM193 it's most likely a dry BCG though.
    I just took the BCG down and cleaned the chamber. It was dirty, but not enough for me to consider it "dirty"... if you know what I mean. I usually do a few range trips, or a couple hundred rounds before I clean it. It's sparkling fresh now. I'm going to try not to worry about it too much unless it continues to happen. The only problem is I don't get the range often. I do a good bit of dry practice in the house but don't get a lot of time to live fire. This is the first time I had to the AR to the range in about a month. My work schedule rotates and the range was busy today so I don't really get to shoot how I want to shoot because of all the people there.

    I try to make sure the BCG is lubed up well, but that is one thing I didn't do on this trip.

  12. #11
    VIP Member Array jonconsiglio's Avatar
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    On a side note here, I'd step up to an H2. A 16" carbine gassed rifle running 5.56 will probably run at more consistent velocities with an H2. It's very possible for short stroking to occur due to the carrier traveling too fast.

    Now, as already mentioned, an AR cannot fire unless the bolt is fully seated. My very rough guess without seeing it first hand would be ammo (but this is m193, so that's better than a lot of others) then another option could be the hammer spring, which I doubt.

    What happens with over gassing is the carrier begins to move before the bolt is fully unlocked. When it does unlock, part of the energy is already used up, so it short strokes, often leading people to mistakenly think the fix is a lighter buffer, when it's actually a heavier buffer.

    The other problem is bolt bounce. If the carrier is dry, as already mentioned, it is possible for it to travel forward then bounce back, just enough to take it out of battery.

    In any event, I'd throw an H2 in there, at least when shooting 5.56 ammo.

    Get yourself some Slip EWL and cover the bolt and carrier liberally. A dirty, well lubed AR will run for thousands of rounds. A dry AR, or so much.
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  13. #12
    Distinguished Member Array RKM's Avatar
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    Quote Originally Posted by jonconsiglio View Post
    On a side note here, I'd step up to an H2. A 16" carbine gassed rifle running 5.56 will probably run at more consistent velocities with an H2. It's very possible for short stroking to occur due to the carrier traveling too fast.

    Now, as already mentioned, an AR cannot fire unless the bolt is fully seated. My very rough guess without seeing it first hand would be ammo (but this is m193, so that's better than a lot of others) then another option could be the hammer spring, which I doubt.

    What happens with over gassing is the carrier begins to move before the bolt is fully unlocked. When it does unlock, part of the energy is already used up, so it short strokes, often leading people to mistakenly think the fix is a lighter buffer, when it's actually a heavier buffer.

    The other problem is bolt bounce. If the carrier is dry, as already mentioned, it is possible for it to travel forward then bounce back, just enough to take it out of battery.

    In any event, I'd throw an H2 in there, at least when shooting 5.56 ammo.

    Get yourself some Slip EWL and cover the bolt and carrier liberally. A dirty, well lubed AR will run for thousands of rounds. A dry AR, or so much.
    Thanks, Jon. I'll give those things a try. I've actually had an H2 buffer in my shopping cart on bravocompayusa.com for a few weeks now. Just always thought "do I really need it?". I was actually considering it because I loved how stepping up to an H buffer made recoil feel, so I wanted to step to an H2 for that same reason. Bolt bounce did come to mind. Reliability had nothing to do with why I wanted an H2, until now.

    One day when my barrel wears out, I'll get a good Mil-spec 1:7 barrel with a proper sized gas port. But until then, the stock M&P barrel is just fine.

    I'll throw an H2 in there before my next trip to the range and see how it goes. And if I come across the problem again, I'll remember to check the things every has mentioned.

    I had my ruger 10/22 out to sight in the Eotech, and this is the first range trip that it ran with NO malfunctions. It's a sad day when a 10/22 out runs a 5.56 AR :( haha. I never really cared when my 10/22 malfunctions because it's just a .22, usually just because I'm using cheap mags of it's dirty.

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