Ar15 wont go into battery

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  • d.kaufman

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    Finally got a chance to take one of my ar15s out and it wont run.
    Heres the deal. BCI lower with cmmg parts kit and mil spec trigger. Complete BCA 18" upper with 1:7 twist 223 wylde barrel. Cant remember for sure what brand bcg but i believe toolcraft and the charging handle is a cheapo ambi handle.
    So what happens is i pull charging handle back and let her rip. Chambers round and fires first shot. It chambers next round but bcg wont go all the way into battery. Roughly 1/2" short. Forward assist will not push the bcg into full battery, and pulling on charging handle cannot be done. It has to be lightly tapped with rubber mallet to pull charging handle back. I can slam buttstock on ground and it will go full battery and fire round. Only did this twice. When testing with spent case doesnt matter if its 223 or 556 or steel v/s brass. They all act the same.
    If i seperate upper from lower and with no round the bcg slides right down to fully closed under its own weight. Same with upper and lower pinned together. So not a gas tube alignment issue i dont believe. If i stick a spent casing in the chamber the bcg will not go fully forward unless i let the charging handle go as intended, but then have to use the mallet to pull charging handle back to eject casing.
    What i have done is swapped complete lowers, bcg and charging handles and still same issue. One thing i noticed is there is some drag with the cheapo handle in the upper and when i swap with a strike industries that one doesn't drag but still same issue.
    Im guessing slightly out of spec upper but not 100% positive. With no round in chamber the bcg goes right on down under its own weight so not sure that it would be a barrel extension issue.
    Anyone got any ideas what the issue could be?

    This was a cheapo build with stuff i had lying around other than the complete bca upper.

    If you need a pic to help me out please let me know what youd like a pic of and I'll happily take one and post it.

    I've put together pretty much every ar i own from scratch, including complete upper assembly and never had issues. This is the only complete factory upper I've ever bought and consequently the only one ive had issues with...go figure

    Any help or ideas/ thoughts would be greatly appreciated.
    Thanks in advance INGO!
     

    JJFII

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    sounds to me like you BCG locking lug that rotates the bolt is out of spec. Head space could be off as well. I'd stop firing it.
     

    d.kaufman

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    Ive tried another complete lower, bcg, charging handle, mags, steel vs brass cased, 223 vs 556 ammo etc.

    I only fired a total of 3 rounds. The only 3 rounds thru this set-up. All testing since has been with an empty/spent case. I dont plan putting anymore rounds thru it till the problem is found out.
     

    rob63

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    If the barrel extension fit loosely into the upper and they didn't bother to shim it when they installed the barrel, then it could have ended up slightly cockeyed after they tightened the barrel nut. Thus, the chamber would be slightly misaligned with the bcg. That would explain why it shows up when chambering a round, but not otherwise. If it is also slightly undergassed, that would explain why it will chamber the first round when the bolt is pulled all the way back, but not after it has been fired since the bcg isn't going back as far.

    If you can't return the upper, then I would remove the barrel and see how well it fits into the upper. Just my :twocents:
     

    d.kaufman

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    If the barrel extension fit loosely into the upper and they didn't bother to shim it when they installed the barrel, then it could have ended up slightly cockeyed after they tightened the barrel nut. Thus, the chamber would be slightly misaligned with the bcg. That would explain why it shows up when chambering a round, but not otherwise. If it is also slightly undergassed, that would explain why it will chamber the first round when the bolt is pulled all the way back, but not after it has been fired since the bcg isn't going back as far.

    If you can't return the upper, then I would remove the barrel and see how well it fits into the upper. Just my :twocents:

    Yeah. Thats my next point of attack. I was thinking if the extension was offset a bit though that the bcg wouldn't just slide right down into extension under its own weight. Thought id see if there was some suggestions before i tear it down. My email bca and see what they have to say, but i probably bought this upper over a year ago or so. Have to many others i shoot when i get a chance, so this was first time out with this one
     

    d.kaufman

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    If the barrel extension fit loosely into the upper and they didn't bother to shim it when they installed the barrel, then it could have ended up slightly cockeyed after they tightened the barrel nut. Thus, the chamber would be slightly misaligned with the bcg. That would explain why it shows up when chambering a round, but not otherwise. If it is also slightly undergassed, that would explain why it will chamber the first round when the bolt is pulled all the way back, but not after it has been fired since the bcg isn't going back as far.

    If you can't return the upper, then I would remove the barrel and see how well it fits into the upper. Just my :twocents:

    Forgot to mention that it does chamber the next round just fine but bolt wont go into full battery. It stops about 1/2" short. Just pulled it apart, took barrel nut off and backed barrel out of upper about half inch, bolt still wont close with a case in chamber. Its got to either be an out of spec upper or out of spec barrel/extension is all i can figure. The bcg works just fine in a different ar, so cant be that.
     

    d.kaufman

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    Got it figured out. Something is wrong with the ejector/spring assembly. It does not push in and is stopping the bolt from going into full battery. Im guessing the reason why when i tried a different bolt on an empty case is beacuse the original bolt is messing up the rim of the case. I took a brand new empty case and used the different bolt and all is well.
    Time to order a few parts
     

    bwframe

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    This is a good lesson also. Always good to have an extra BCG in the range bag. That or err on the side of taking an extra gun that you aren't necessarily planning to shoot to borrow a BCG from for diagnosis. I've seen this solve issues before, but don't necessarily think of it every time myself.

    I'm thinking of getting a big rubber mallet to dedicate to my rifle range bag also. :)
     

    d.kaufman

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    I just took the bcg group apart. I must of got this bcg used off someone. Wrapped around the extractor spring was an o-ring. Now i can honestly say I've never seen this, but i have never taken the extractor out of a bolt before. I usually just clean it some brake cleaner, blow it out with compressed air and lube it up. Looking at parts diagrams i see this is not normal. I had a new extractor spring and pin so i installed that reassembled everything and it function checks just fine.

    And bwframe a rubber mallet has just been added to my range bag. This is probably the only time i didnt have multiple ar15s with me, which definitely would of saved me some time. I had my 308 ar and was breaking in a new 308 bolt action along with shooting my 10/22. Had my daughters 10/22 and her 410 along for the ride and had no more room in the car.
    Go figure.
    Alls well that ends well i guess
     

    jinks

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    I just took the bcg group apart. I must of got this bcg used off someone. Wrapped around the extractor spring was an o-ring. Now i can honestly say I've never seen this, but i have never taken the extractor out of a bolt before.
    The o-ring on the extractor spring has been used a long time to upgrade the bolt on AR type rifles. I saw problems with this setup occasionally when used with a heavy spring.

    The BCM Extractor Spring is so strong the Mil-Spec Crane O-Ring will probably not be needed, but it is included.

    https://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm
     

    churchmouse

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    d.kaufman

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    The o-ring on the extractor spring has been used a long time to upgrade the bolt on AR type rifles. I saw problems with this setup occasionally when used with a heavy spring.

    The BCM Extractor Spring is so strong the Mil-Spec Crane O-Ring will probably not be needed, but it is included.

    https://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

    Thanks for the link. Possibly this was installed and the o-ring wasnt needed then. I replaced the spring and pin while i was in there, omitting the o-ring, since i didnt see it in any diagrams i looked at. It function checks just fine,( no more bolt not going into full battery and having to smack the charging handle with a mallet to pull it back, so i guess i need to get back to the range and test her out
     

    rob63

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    This left me wondering what the purpose of the o-ring would be, so I googled it. Assuming people on other gun forums actually know what they are talking about, it is to aid extraction on carbine length gas systems due to the increased pressures in the shorter system. It is unnecessary, and sometimes problem causing, in mid-length or rifle length gas systems. So sayeth the 'net.
     

    Hohn

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    This left me wondering what the purpose of the o-ring would be, so I googled it. Assuming people on other gun forums actually know what they are talking about, it is to aid extraction on carbine length gas systems due to the increased pressures in the shorter system. It is unnecessary, and sometimes problem causing, in mid-length or rifle length gas systems. So sayeth the 'net.

    Yet another reason that friends don't let friends run carbine gas for >16" barrels.
     

    d.kaufman

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    Guess this is one of those times its not needed, but doesn't have anything to do with gas system being as i couldn't get bolt to close or eject without lots of force, just doing a function check with empty case. Just to be safe though i ordered a new complete bcg to keep on hand for when i do get back to the range to test it out
     

    JJFII

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    that darn o-ring...LOL I actually dont see a real need for it. The only Bolt upgrade I was happy to see...that no one actually does for some reason .... ?? ....is the Armilite enhanced Bolt lugs.
     

    sig1473

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    The only Bolt upgrade I was happy to see...that no one actually does for some reason .... ?? ....is the Armilite enhanced Bolt lugs.

    Uh, what? I'm guessing you've never heard of KAC's E3 bolt or LMT's enhanced bolts. I have both. The KAC has a 20,000rd warranty on the bolt. The LMT is made of Aermet 100.

    LMT
    LMT_Enhanced_Full-Auto_Bolt_Carrier_Group_L7Q3_E.jpg


    KAC E3
    e3-spare-bolt.jpg
     

    d.kaufman

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    Uh, what? I'm guessing you've never heard of KAC's E3 bolt or LMT's enhanced bolts. I have both. The KAC has a 20,000rd warranty on the bolt. The LMT is made of Aermet 100.

    LMT
    LMT_Enhanced_Full-Auto_Bolt_Carrier_Group_L7Q3_E.jpg


    KAC E3
    e3-spare-bolt.jpg

    Interesting. I see the kac e3 is only compatible with their barrel extension. Not much of an option there. Over $200 as well for just the bolt. Definitely not an option on a budget build thats just for plinking.

    Lmt not much better priced but at least doesnt look like you need a proprietary barrel extension.

    This is the first failure ive ever had on any of the ar platforms I've owned due to a bolt.
    My more expensive builds i use the fail zero and have nothing but success with them. And thats what i ordered this morning to keep in the range bag for a backup
     
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