Target Sports

BCG Problem?

The #1 community for Gun Owners of the Gulf Coast States

Member Benefits:

  • Fewer Ads!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    I purchased a complete 5.56 pistol upper to go on the lower I use for my 300 Blackout pistol. It is a Dirty Bird Midnight Edition upper. It's not the most expensive, but it had good reviews. I gave it a try and the bolt would not close without pushing the assist button. After pushing the assist button it appeared to be in full battery, but would not fire. I assume that it is still no going into full battery. I took the BCG out of my 300 Blackout upper, and put it in the 5.56 upper. When I tried this I had to push the assist button to make it go into full battery, but it fired fine. It also cycled multiple rounds with no problem.

    What do y'all think the problem is with the BCG that came with the 5.56 upper?

    Sent from my SM-G955U using Tapatalk
     

    wildrider666

    Master
    Rating - 0%
    0   0   0
    Joined
    Sep 26, 2012
    Messages
    8,753
    Points
    113
    Location
    Panama City Beach, Fl
    With the Upper and BCG, you should be able to fully seat BCG into Battery with finger pressure.
    Chamber and barrel extention clean, no burrs? Same on bolt locking lugs? Headspace Go, No-Go gauge test.

    Didn't you have this or a similar 300 BO headspace issue before?
     

    mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    With the Upper and BCG, you should be able to fully seat BCG into Battery with finger pressure.
    Chamber and barrel extention clean, no burrs? Same on bolt locking lugs? Headspace Go, No-Go gauge test.

    Didn't you have this or a similar 300 BO headspace issue before?
    Not the same problem with the 300. I built the 300 including installing the barrel, and couldn't get it to go into battery with the GO gauge. It turned out the New gauge was out of spec. Once I got another gauge it worked fine.

    I bought this 5.56 upper complete, so I assumed they have already checked it with gauges before they shipped it. When I tried a different BCG it cycled fine after pushing the assist button to get started. I need to check for burrs.

    I have contacted Dirty Bird to see what they will say.

    Sent from my SM-G955U using Tapatalk
     

    Daezee

    Master
    Rating - 100%
    13   0   0
    Joined
    Dec 17, 2012
    Messages
    3,355
    Points
    113
    Location
    Milton
    Hard to diagnose without examining, but

    1). Firing pin in wrong position when firing pin retaining pin installed.

    2). Gas rings too snug meaning more force is needed to put bcg into fully forward position. Possible solution is it needs breaking in by manipulating it in and out of lockup. And/or take bcg apart and examine gas rings.
     
    • Like
    Reactions: FLT

    Daezee

    Master
    Rating - 100%
    13   0   0
    Joined
    Dec 17, 2012
    Messages
    3,355
    Points
    113
    Location
    Milton
    Did the new bcg function in your Blackout upper?
     

    wildrider666

    Master
    Rating - 0%
    0   0   0
    Joined
    Sep 26, 2012
    Messages
    8,753
    Points
    113
    Location
    Panama City Beach, Fl
    1st BCG had FWD assist and still not far enough to seat in Battery/fire.
    2nd BCG and "still" needed to use of FWD assist to manually chamber but did fire.

    As you know, you should never have to use the Fwd assist with clean, proper, parts and ammo. Might help to manually "cycle" break in, letting buffer spring slam it into Battery a hundred times(+-) without a cartridge. You could check it with an "empty case" to see if it wears into full Battery and lets the hammer fall.

    Is ammo out of spec for the possible tight chamber? Try different Brand of ammo?
     

    mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    Ok update. I think it is going into battery, but there is something up with the firing pin. I haven't taken the BCG apart yet, but when I compress it in my hand and push up on the firing pin it does not protrude. Could the firing pin be short?
    95f4d882056c9a029d45606a7ebcfda3.jpg


    Sent from my SM-G955U using Tapatalk
     

    wildrider666

    Master
    Rating - 0%
    0   0   0
    Joined
    Sep 26, 2012
    Messages
    8,753
    Points
    113
    Location
    Panama City Beach, Fl
    Is the bolt cam pin moving the full distance in the cam slot, allowing the bolt to fully turn within the Carrier to Lock?

    You can compare the firing pins for irregularities.
    You can insert the firing pin tip into JUST THE BOLT from the rear to check freedom of movement and ability to protrude past the bolt face.

    Does the firing pin freely move through the hole in the cam pin?

    With the firing pin retaining pin and cam pin removed and bolt fully seated in BCG: will the firing pin protrude adequately out of the bolt face: Good?
    Now install cam pin and check protrusion: Good?
    Now correctly install the firing pin retaining pin in relation to the firing pin and check protrusion: Good?
     

    Murfpcola

    Master
    Rating - 100%
    3   0   0
    Joined
    Apr 15, 2016
    Messages
    1,831
    Points
    113
    Location
    Pensacola
    Maybe barrel extension is tight? Female part that the locking lugs turn into. Strange for two BCGs to require FA to be pushed. Much more experienced people than me already chiming in though.
     

    mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    Is the bolt cam pin moving the full distance in the cam slot, allowing the bolt to fully turn within the Carrier to Lock?

    You can compare the firing pins for irregularities.
    You can insert the firing pin tip into JUST THE BOLT from the rear to check freedom of movement and ability to protrude past the bolt face.

    Does the firing pin freely move through the hole in the cam pin?

    With the firing pin retaining pin and cam pin removed and bolt fully seated in BCG: will the firing pin protrude adequately out of the bolt face: Good?
    Now install cam pin and check protrusion: Good?
    Now correctly install the firing pin retaining pin in relation to the firing pin and check protrusion: Good?
    I will try this procedure tomorrow.

    Sent from my SM-G955U using Tapatalk
     

    FrommerStop

    Master
    Rating - 0%
    0   0   0
    Joined
    Apr 7, 2016
    Messages
    6,897
    Points
    113
    Location
    NWFL
    1st BCG had FWD assist and still not far enough to seat in Battery/fire.
    2nd BCG and "still" needed to use of FWD assist to manually chamber but did fire.

    As you know, you should never have to use the Fwd assist with clean, proper, parts and ammo. Might help to manually "cycle" break in, letting buffer spring slam it into Battery a hundred times(+-) without a cartridge. You could check it with an "empty case" to see if it wears into full Battery and lets the hammer fall.

    Is ammo out of spec for the possible tight chamber? Try different Brand of ammo?
    The original M16 was not designed with a forward assist. If a round does not chamber when the BCG goes forward under normal spring force, eject round and try to chamber another. it is possible to jam up an AR badly with an out of spec round if the forward assist is used to forcibly chamber a round and the bolt is not able to close.
    The AR-15 forward assist was added to the rifle at the behest of the Army as Eugene Stoner (and the Air Force) actually didn’t believe it was necessary on his design that became the M16. (Again, we’ll get to that in a bit.) Colt created the forward assist assembly, including a pawl (the thing you hit) a plunger (which engages with the receiver to send it forward) a spring and a roll pin. To actuate, you press the pawl, pushing the plunger forward. That engages with teeth on the receiver, pushing it forward.
    More discussion at https://www.thetruthaboutguns.com/ar-15-forward-assist/
    Time when can make good sense to use the forward assist
    1. It allows the bolt to be closed silently. This is important in hunting, and could be important for anyone in a combat, law enforcement, or self-defense situation in certain circumstances. There are plenty of stories of hunters in close proximity to game who needed this functionality. Perhaps they rode the charging handle when they initially chambered their round and the bolt wasn’t in battery. Or perhaps they forgot to charge the gun in the first place. In both cases, silently driving the bolt carrier home with the forward assist provides a full or partial solution.


    2. It allows a short-chamber. If a person, or just a dropped gun, comes out of the water with an M4, pulling the bolt back slightly allows the water to drain from the bore. Pushing the forward assist makes sure it goes back into battery.


    3. It can be used for a chamber check to make sure a round is chambered. Pull the bolt back just far enough to check for a cartridge, then use the forward assist to ensure the bolt goes fully into battery. Many people do chamber checks this way.


    4. If an AR-15 pattern rifle is too dirty to cycle properly using the forward assist can allow the shooter to stay active and engaged albeit in a manner more closely resembling a single shot rifle. This has been “required” in a number of engagements in the last few years by soldiers whose rifles were too dusty, dirty, and dry to function. I don’t personally see this as a good use of the forward assist, since in my opinion most of these situations could have been avoided with better discipline and training. However, if a soldier lacks the discipline to keep his weapon clean and lubed, use of the forward assist may save his life.
     

    mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    Is the bolt cam pin moving the full distance in the cam slot, allowing the bolt to fully turn within the Carrier to Lock?

    You can compare the firing pins for irregularities.
    You can insert the firing pin tip into JUST THE BOLT from the rear to check freedom of movement and ability to protrude past the bolt face.

    Does the firing pin freely move through the hole in the cam pin?

    With the firing pin retaining pin and cam pin removed and bolt fully seated in BCG: will the firing pin protrude adequately out of the bolt face: Good?
    Now install cam pin and check protrusion: Good?
    Now correctly install the firing pin retaining pin in relation to the firing pin and check protrusion: Good?

    - The Bolt Cam Pin is moving the full distance in the Cam Slot.
    - The Firing Pon does move freely through the hole in the Cam Pin.
    - With the firing pin retaining pin and cam pin removed and bolt fully seated in BCG the Firing Pin does not protrude.
    - With Cam Pin installed it does not protrude.
    - With everything correctly installed the Firing Pin does not protrude.


    I let the manufacturer know about the issue, and they said it is out of spec. They are going to send me a new BCG with a return label for the bad one.

    Sent from my SM-G955U using Tapatalk
     

    mtbbrewer74

    Master
    Rating - 100%
    3   0   0
    Joined
    Jul 13, 2015
    Messages
    1,585
    Points
    63
    Location
    Milton
    Oh and here is a picture of the Firing Pin with the issue on the Left, and it is compared to the Firing Pin out of my 300 on the Right. It may be hard to tell but the bottoms are lined up even. The one with the issue is definitely shorter.
    8ce99f1ffbc6937a36139dbfde9c11a6.jpg


    Sent from my SM-G955U using Tapatalk
     

    Light82

    Expert
    Rating - 0%
    0   0   0
    Joined
    Jan 12, 2013
    Messages
    150
    Points
    28
    Location
    Pensacola Fl
    I had this problem when I bought an upper and a nickel boron coated BCG from two different companies. When I took the pieces to my armorer buddy he said even though each piece was within tolerances, combined the two of them wouldn’t fit since each was a little off. After trying a couple different BCGs we found a BCG that fit. Turns out this happens more frequently on NiB BCGs. Now I buy both parts together. Try a different BCG would be my advice.
     

    FrommerStop

    Master
    Rating - 0%
    0   0   0
    Joined
    Apr 7, 2016
    Messages
    6,897
    Points
    113
    Location
    NWFL
    I had this problem when I bought an upper and a nickel boron coated BCG from two different companies. When I took the pieces to my armorer buddy he said even though each piece was within tolerances, combined the two of them wouldn’t fit since each was a little off. After trying a couple different BCGs we found a BCG that fit. Turns out this happens more frequently on NiB BCGs. Now I buy both parts together. Try a different BCG would be my advice.
    It is handy to have alternate parts on hand with an AR or anygun when you are having unexplained problems with function. Sometimes changing out one part for another will fix things.
     
    Top Bottom