So I just completed my BCM build

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    Member Array gixx1070's Avatar
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    So I just completed my BCM build

    So I am running a mid 14.5 BCM upper with BCM lower and H buffer. Everything is brand new including the pmags. Took it out today and I kept getting ftf I think might be fte, it seems like the bcg was trying to load two rounds at once.

    Ammo was pmc bronze 55g fmj
    And federal 223 rem 55 g fmj from walmart. I know BCM recommends mil spec pressure ammo with the H buffer so I guess my question is. The ammo listed above is it under powered for the H buffer?? This really sucks paid a lot for these parts and it doesn't run.
    Thanks for any input.

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    RKM
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    I don't have a BCM rifle but I've never had problems using PMC .223 with an H buffer and BCM BCG. Is it failing to eject the spent round and then feeding a fresh one into it? Or is it trying to feed two fresh rounds at the same time (mag problem). I'm not super duper knowledgeable about AR failures. Does this happen with both magazines? Try different ammo (5.56, not .223) and magazines before you come to any conclusions.

    That's my amateur advice.

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    Member Array gixx1070's Avatar
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    Thanks for the help. Yes it will not eject spent case then it loads a new round causing the problem. I got it once to cycle about 10 rounds without problems and it was with another new pmag. So I thought it was the mag but after that 10 it went back to the problem. I am completely new to this platform so please bare with me. From what it looked like to me was the extractor didn't look like it was grabbing the spent case right but I may be wrong. The bcg is brand new from PSA.

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    Do you have the black insert as well as the spring under the extractor?
    Last edited by gasmitty; January 8th, 2012 at 09:59 AM. Reason: incorrectly said "O-ring" instead of insert
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    If you're getting a double feed (two rounds trying to chamber at the same time), the only cause for that would be the magazine(s). If it's not extracting the spent case but trying to chamber a fresh round with that spent case still in the chamber, that's a bad extractor. It's hard to diagnose a problem over the Internet, but that looks like a classic double feed to me. How many mags was this happening with? Was it different mags or always the same one?
    Proven combat techniques may not be flashy and may require a bit more physical effort on the part of the shooter. Further, they may not win competition matches, but they will help ensure your survival in a shooting or gunfight on the street. ~Paul Howe

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    RKM
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    I'm not an expert on the platform either, I'm still learning. I'd still try hotter 5.56 ammo just to see what happens. If you're still having problems, try a different bolt. Even if the bolt isn't the problem, it's not a bad idea to have one on hand. I'd buy an extra bolt anyway. You get a lot of spare parts with a bolt... gas rings, extractor, extractor spring and insert and ejector. If anything, it could be a problem with the ejector. Seems like the extractor is doing it's job, the casing just isn't making it's way out of the ejection port.

    Currently out of stock, but check back daily
    BCM AR15 Bolt Assembly MPI

    The bolt itself isn't the problem. But having a spare is nice. Throwing in a different bolt (since it comes with all new parts) will likely eliminate any problem with ejection or extraction, if the problem lies within the ejector or extractor themselves.

    Somebody more knowledgeable than myself should be able to give you a better answer, but that's my suggestion.

    EDIT: And there is Jon. He'll take care of you.

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    Member Array gixx1070's Avatar
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    It happened with 2 different mags both pmags. Sorry for the crappy pics from my phone, the top round is the spent case getting lodged either to the top or the side of the barrel. Yes there is a black o ring on the PSA bcg, I think I will order one from BCM tonight.

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    VIP Member Array jonconsiglio's Avatar
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    I missed the OP's second reply. There's a few steps in a particular order you need to take to diagnose and fix the issue. It's a simple problem and you'll be good to go before you know it. When do you plan on hitting the range again? I'll be free tomorrow in the morning and I can help you out.

    I'll post in this thread when I have some time to help you out, it should be early. I just found out my Dad is pretty sick, so I'm a bit of a mess, but I'll be able to walk you through a few things. Keep in mind, we start with the most simple, even if you don't think that's the problem, and go from there. We don't want to replace the mags, bolt, buffer and ammo all at the same time, for example. We'll start at the moat likely and easiest to fix and go from there.
    Proven combat techniques may not be flashy and may require a bit more physical effort on the part of the shooter. Further, they may not win competition matches, but they will help ensure your survival in a shooting or gunfight on the street. ~Paul Howe

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    Member Array gixx1070's Avatar
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    Sounds good, I'm planning on going to buy hotter ammo tomorrow morning and trying that out. I did order a standard buffer and spring from BCM tonight. Family is more important so let me know when it's cool for you.
    Thanks

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    VIP Member Array jonconsiglio's Avatar
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    Quote Originally Posted by gixx1070 View Post
    It happened with 2 different mags both pmags. Sorry for the crappy pics from my phone, the top round is the spent case getting lodged either to the top or the side of the barrel. Yes there is a black o ring on the PSA bcg, I think I will order one from BCM tonight.
    The o-ring needs to come out. Let's start there. It's only needed when you have violent extraction and really need the extractor to grab the case rim. You want the 5 coil spring and black insert but not the o-ring to start with. Remove the o-ring and choose one mag only to use and we'll start there.

    Do you have different types of ammo or just the one you used? Let's use the ammo you'll shoot the most. That's why BCM includes the o-ring but does not have it installed, it's an "as required" part and usually it's not required on a 14.5".
    Proven combat techniques may not be flashy and may require a bit more physical effort on the part of the shooter. Further, they may not win competition matches, but they will help ensure your survival in a shooting or gunfight on the street. ~Paul Howe

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    Member Array gixx1070's Avatar
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    Jon the bcg is from palmetto st armory does that matter?

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    VIP Member Array dukalmighty's Avatar
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    Is the BCG (Bolt Carrier Group)Lubricated or are you running it too dry,that's where I would start first
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    Member Array gixx1070's Avatar
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    No it was wet I took some frog lube paste with me to the range in case of lube problems. Once the problem started I took the bcg apart and lubed everything inside none of that helped.

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    VIP Member Array jonconsiglio's Avatar
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    There's a few things this could be. I'd want to start with removing the o-ring. From there, if we determine that's not it and it's not magazine related, we'll try 5.56 pressure ammo. If that doesn't do it, I'd suspect the carrier key or the another type of gas leak.

    This would be much easier if I was holding the rifle!

    For some reason I'm thinking it's a 50/50 chance it's the o-ring. The extractor is so tight, it's either not snapping over the rim or it's biting too tight. Does any of the extracted brass have marks on the rim?
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    Proven combat techniques may not be flashy and may require a bit more physical effort on the part of the shooter. Further, they may not win competition matches, but they will help ensure your survival in a shooting or gunfight on the street. ~Paul Howe

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    Member Array Aiko's Avatar
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    Not sure to be honest. I shoot both PMC and Fed out of my DD and BCM/H buffer with zero issues. I would be inclined to think proper lube, try different mags and swap a different BCG.

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