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Posted: 3/21/2014 1:37:16 AM EDT
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Hey guys, first time AR builder/owner long time gun enthusiast here. I recently made an AR15 and have been having some cycle problems. Sometimes the gun will double feed, sometimes it will fail to eject and sometimes it will not lock back on a empty magazine, all leading me to believe its under gassed. This isn't a constant problem but more like a once in a blue moon problem.
I've tried different ammo types, checked and double checked my gas block and tube. I've ran every diagnostic test I could think of or found on the internet and everything checks out. However I recently came across an ejection pattern chart and upon paying attention noticed my brass was ejecting between 4-6 o clock, mostly 6ish. The chart said lighter buffer/spring. I am unsure what type of spring and buffer I got since it came in a vltor stock kit but was wondering if it would be worth it to get a light spring/buffer? I am currently not in the best place to spend cash mindlessly now but my AR is my SHTF gun and I want to ensure it is I'm top notch condition. If a lighter spring and buffer might fix all of my before mentioned problems it would be worth the cash. Thanks for your time. |
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Ejection patterns very rarely have anything to do with the function of the rifle, except in people's minds. Focus on the direct symptoms and fix those. How new is the rifle and what type of ammunition are you using? Until you've run a couple hundred rounds of the good stuff (brass cased, preferably 5.56 loads) through your rifle, I wouldn't start messing with anything. When you mention double feeds, do you actually mean a failure to eject coupled with a failure to feed (an extractor, ejector, or rough chamber issue)? Or 2 live rounds (a magazine issue that might also explain not locking back). From the first line in your post, I'm leaning towards a breaking in period where the rifle stumbles on .223 loads. Run some 5.56 loads through it and then reevaluate the rifle's function. As the mating surfaces of the bolt carrier, upper receiver, and hammer smooth themselves out against each other, you'll probably notice the problem go away. A run down of your parts suppliers may also give further clues. |
| good evening, just registered and was researching topics, I recently acquired a new build in 6.8 SPC, the upper is a new YHM with spikes BCG and spikes complete lower with st-2 buffer. I am also having ejection problems. I shot approx. 100 rounds of hornady v max ammo. I was advised to use the st-3 heavy buffer. should I run more rounds before trying another buffer? thanks for your help |
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good evening, just registered and was researching topics, I recently acquired a new build in 6.8 SPC, the upper is a new YHM with spikes BCG and spikes complete lower with st-2 buffer. I am also having ejection problems. I shot approx. 100 rounds of hornady v max ammo. I was advised to use the st-3 heavy buffer. should I run more rounds before trying another buffer? thanks for your help I don't think it has anything to do with the YHM or Spikes compatibility. Both of those manufacturers are solid. I would try a different ammo. My experience with hornady is that they make a really premium ammo that isn't necessarily premium for every gun. Try the good old federal ammo and see what happens. 6.8 is still a relatively new market. Not that Hornady doesn't know what they're doing, because they do... but, to me it feels like the market their ammo toward specific weapons, while others make a general purpose round. I could be completely wrong, but that's just my experience with them. Only other thing to do is check the extractor and make sure the rubber donut is around the spring and not missing somewhere. It may be a $20 fix with a new extractor. If there is not enough pressure on the case as it's pulled from the chamber, the cartridge can slip off the extractor and cause the ejecting pin to strike it with less authority. Otherwise, yes, try a new buffer. |
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The rifle is actually a few months old and has a good number of rounds through it. I would say it has well over 100 rounds through it.
As far as the double feed it is trying to feed two live rounds into the chamber at the same time. It has happened with a few different types of magazines and I have made sure they were all in good condition. Basically I have checked everything there is to check and my only guess now is the buffer/spring being to heavy for the gun. It is a m4gory, so it has a carbine length gas system on it. Lower - Ares Armor 80% Billet – Machined by me of course. - CMMG Lower Parts Kit - VLTOR buffer tube, buffer srping and buffer and stock kit - Magpul ASAP Sling Plate - Some Generic “California Legal” Bullet Button - A enhanced trigger guard Rear of Upper - Rock River Arms Forged A4 - Rock River Arms Forward Assist - Double Star Charging Handle - Ice Arms Nitrided M16 9310 Bolt Carrier Group - Custom “Zombie Hunter” Dust Cover - GRG Iron Sights Front of Upper - Yankee Hill Diamond Quad Rail - 16” 1-9 twist, Carbine Length Gas System, Chrome-Moly Black Nitride, wylde chambered, Bergara Barrel - Yankee Hill Low Profile Gas Block - Yank Hill Carbine Gas Tube - DPMS Flash Hider Rail Accessories - TMS QD Sling Swivel - Magpul AFG 1 - NCStar offset Light Mount - Techlight Lumen Master |
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It sounds like what you have is a typical undergassed problem.
Usually caused by: an improperly located gas block, or a improperly secured gas block, or a leaking gas block, or a loose carrier key on a newer build. Messing with the buffer to try to cure a ejection problem (which is a symptom of the undergassed problem in this case) is not going to fix the problem. |
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I am pretty confident the Gas block is properly installed. I tested it out by blowing smoke down the tube and it came out into the barrel and I never saw it leak out. It is fastened as instructed and seems to be lined up properly with the hole in the barrel. I've also took it off and re-installed it again being OCD and tested it and it still seemed to be properly lined up. As for the key I found a trick on YouTube about spraying it and then using a straw to blow air into it to see if it was leaking and I saw no bubbles leading me to believe it is in working condition too. I've been researching this topic for about a month now, trying every trick I've found on YouTube and here on the AR15 forums. I guess I could always check things out again but I am confident in saying it's not a problem in the gas system.
I am lead to believe it might be that I need a lighter BCG, Buffer or spring, however I have yet to find anything saying that replacing those will fix the problems I am having with the gun. Generally everyone says its a gas issue, but I don't know what type of buffer kit I got since it just came in a kit and leads me to believe I might of got one that is to heavy for my gun to function properly. Before I spend the money though I wanted confirmation pretty much that this MIGHT help fix my problems. |
| VLTOR buffer tube, buffer srping and buffer and stock kits that I've seen all come the standard carbine buffer. If nothing is stamped in the face of the buffer, it's a standard weight. Being a Bergara barrel I'd be measuring the gas port, recall reading that more than a few had inadequate hole size. |
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Sorry I have been busy with life so my response was delayed, but I checked all of this out again and everything seemed to spec. I even measured the gas port on the barrel and it fell within spec :/ Could it be that I got a bad part someone else?
My main problem really is that I am just at a lost as what to do and I really don't want to throw money into it I don't have right now. I've checked everything over and over and it all seems to be in spec, when I run the upper on a friends lower it seems to work flawlessly and yet their upper on my lower more or less has the same problem. This is another reason I really doubt it's my gas system. Plus I built two rifles, to the same spec, as in the same exact parts piece for piece and that one has the same exact problem. I probably should have mentioned this a while ago. Really it's like a rare problem, I can go to the range and shoot hundreds of bullets without a hitch one day, and then have this happen once or twice another day. I know guns are not perfect but it seems to happen way more then it should, as a SHTF gun I want this thing to be flawless, but I guess I should of spent more on it when building it then :/ oh well, it was my first so it's something I'll remember later on down the road. Right now the only thing I can really say I haven't done is replace my spring, buffer or BCG but it seems to be the generally consensus here that none of those would be a problem leaving me even more at a lost as what to do :( I don't know it just seems like its more complicated then it should be. |
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Sorry I have been busy with life so my response was delayed, but I checked all of this out again and everything seemed to spec. I even measured the gas port on the barrel and it fell within spec :/ Could it be that I got a bad part someone else? My main problem really is that I am just at a lost as what to do and I really don't want to throw money into it I don't have right now. I've checked everything over and over and it all seems to be in spec, when I run the upper on a friends lower it seems to work flawlessly and yet their upper on my lower more or less has the same problem. This is another reason I really doubt it's my gas system. Plus I built two rifles, to the same spec, as in the same exact parts piece for piece and that one has the same exact problem. I probably should have mentioned this a while ago. Really it's like a rare problem, I can go to the range and shoot hundreds of bullets without a hitch one day, and then have this happen once or twice another day. I know guns are not perfect but it seems to happen way more then it should, as a SHTF gun I want this thing to be flawless, but I guess I should of spent more on it when building it then :/ oh well, it was my first so it's something I'll remember later on down the road. Right now the only thing I can really say I haven't done is replace my spring, buffer or BCG but it seems to be the generally consensus here that none of those would be a problem leaving me even more at a lost as what to do :( I don't know it just seems like its more complicated then it should be. Measure that gas port and tell us its size. Tell us if there's a pattern to the problems occurring with a specific brand and type of ammunition. And lube up that action spring and buffer and re-try. It sounds to me like your gun is "marginally-gassed", meaning that it functions with most, but not all loads. I have one like that, and have had to commit to running it with full-power 5.56 NATO-spec ammo; as long as I do that, it runs fine, but if I slip in some mid-power hand loads or budget 223, it'll occasionally choke. HTH 
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As far as the double feed it is trying to feed "two live rounds" into the chamber at the same time. Problem is in the mags alone. Either the follower is binding to the inside of the mag and not allowing the follower to recover quick enough (pulling the mags down and CLP cleaning them/deburing the followers may solve the problem), or the feed lips of the mags are not correctly formed (no saving this), and why the mag is fountain spraying the rounds out instead. And the reason that you are only getting 2 live rounds when it start to fountain spray the round outs, there is not enough room in the action to get any more out of the mag . |
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Measure that gas port and tell us its size. Tell us if there's a pattern to the problems occurring with a specific brand and type of ammunition. And lube up that action spring and buffer and re-try. It sounds to me like your gun is "marginally-gassed", meaning that it functions with most, but not all loads. I have one like that, and have had to commit to running it with full-power 5.56 NATO-spec ammo; as long as I do that, it runs fine, but if I slip in some mid-power hand loads or budget 223, it'll occasionally choke. HTH Quoted:
Measure that gas port and tell us its size. Tell us if there's a pattern to the problems occurring with a specific brand and type of ammunition. And lube up that action spring and buffer and re-try. It sounds to me like your gun is "marginally-gassed", meaning that it functions with most, but not all loads. I have one like that, and have had to commit to running it with full-power 5.56 NATO-spec ammo; as long as I do that, it runs fine, but if I slip in some mid-power hand loads or budget 223, it'll occasionally choke. HTH I can't be 100% sure because it was such a small number, but I got something around .070 when I last measured it which I do believe in my research falls into the proper specs right? I use quite a few different brands though. I used some federal, wolf, remington, hornady and some hand reloads. I'll be honest though that I haven't really paid attention to what type of rounds I put into it so I will have to start keeping notes, but I can say they are all .223 so maybe I should just step up to .556. Quoted:
Problem is in the mags alone. Either the follower is binding to the inside of the mag and not allowing the follower to recover quick enough (pulling the mags down and CLP cleaning them/deburing the followers may solve the problem), or the feed lips of the mags are not correctly formed (no saving this), and why the mag is fountain spraying the rounds out instead. And the reason that you are only getting 2 live rounds when it start to fountain spray the round outs, there is not enough room in the action to get any more out of the mag . So it's 100% my magazine? I have quite a few but I tend to only use my magpul magazine when I go out shoot because I hear such great things about them. I will have to try another magazine next time I go out then. |
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I can't be 100% sure because it was such a small number, but I got something around .070 when I last measured it which I do believe in my research falls into the proper specs right? I use quite a few different brands though. I used some federal, wolf, remington, hornady and some hand reloads. I'll be honest though that I haven't really paid attention to what type of rounds I put into it so I will have to start keeping notes, but I can say they are all .223 so maybe I should just step up to .556. Quoted:
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Measure that gas port and tell us its size. Tell us if there's a pattern to the problems occurring with a specific brand and type of ammunition. And lube up that action spring and buffer and re-try. It sounds to me like your gun is "marginally-gassed", meaning that it functions with most, but not all loads. I have one like that, and have had to commit to running it with full-power 5.56 NATO-spec ammo; as long as I do that, it runs fine, but if I slip in some mid-power hand loads or budget 223, it'll occasionally choke. HTH I can't be 100% sure because it was such a small number, but I got something around .070 when I last measured it which I do believe in my research falls into the proper specs right? I use quite a few different brands though. I used some federal, wolf, remington, hornady and some hand reloads. I'll be honest though that I haven't really paid attention to what type of rounds I put into it so I will have to start keeping notes, but I can say they are all .223 so maybe I should just step up to .556. A 0.070" port for a 16" carbine-length gas system should be just fine. Do monitor which ammo is use when the malfunctions occur, though. And if by chance you're running Gen 2 twenty-round PMags, get them out of the mix; lots of issues reported with them. Gen 3 twenties are redesigned, and reportedly are fine, as are Gen 2 thirties. What's the mag limit in CA these days?? |
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If the rifle had a live round, spent round jam, then this would be the rifle with the spent case not ejected out of the action for some reason.
With two live rounds jams, then the mag is spraying two live rounds into the action as the bolt comes back to clear the top of the mag, plain and simple. So if you are sure that its two live rounds that are in the action from the jam, then the problem is in the mag alone. |
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A 0.070" port for a 16" carbine-length gas system should be just fine. Do monitor which ammo is use when the malfunctions occur, though. And if by chance you're running Gen 2 twenty-round PMags, get them out of the mix; lots of issues reported with them. Gen 3 twenties are redesigned, and reportedly are fine, as are Gen 2 thirties. What's the mag limit in CA these days?? Quoted:
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Measure that gas port and tell us its size. Tell us if there's a pattern to the problems occurring with a specific brand and type of ammunition. And lube up that action spring and buffer and re-try. It sounds to me like your gun is "marginally-gassed", meaning that it functions with most, but not all loads. I have one like that, and have had to commit to running it with full-power 5.56 NATO-spec ammo; as long as I do that, it runs fine, but if I slip in some mid-power hand loads or budget 223, it'll occasionally choke. HTH I can't be 100% sure because it was such a small number, but I got something around .070 when I last measured it which I do believe in my research falls into the proper specs right? I use quite a few different brands though. I used some federal, wolf, remington, hornady and some hand reloads. I'll be honest though that I haven't really paid attention to what type of rounds I put into it so I will have to start keeping notes, but I can say they are all .223 so maybe I should just step up to .556. A 0.070" port for a 16" carbine-length gas system should be just fine. Do monitor which ammo is use when the malfunctions occur, though. And if by chance you're running Gen 2 twenty-round PMags, get them out of the mix; lots of issues reported with them. Gen 3 twenties are redesigned, and reportedly are fine, as are Gen 2 thirties. What's the mag limit in CA these days?? It is 10 round limit sadly, along with a bullet button :( I have the model that looks like a 30 round magazine but only holds 10, which I think is sexier then a 10 round magazine in the gun. |
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