Something odd in my bolt

SargeB

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Jan 12, 2022
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I need some help with an issue on a .308 build. I have a rifle that generally performs well. Recently I began noticing 2 things. 1..... the ejected brass is very dirty, and 2.....after some firing the BCG locks up and no matter how hard I pull on the charging handle I cannot get it to budge. I thought maybe the rifle it is over-gassed and hence so dirty and fouled that the cam pin is too fouled to move and the bolt face then cannot turn to unlock from the barrel.

When I took it apart to clean it, 15 of these little fellows fella's out of the bolt.....I am unsure what these are. I am firing Hornady Black 80971 rounds....not my own shitty reloads or anything like that.... 308 Win 168 gr A-MAX® Hornady BLACK® - Hornady Manufacturing, Inc

So my brilliant idea is putting an adjustable gas block on.....which I have done. But in cleaning the weapon before re-assembling it, I saw these things fall out of the bolt. I am sure their presence is what is causing the rifle to lock up.....

Any idea what these are and any idea what may be causing this?

Any help is appreciated.

IMG_5885.jpgIMG_5886.jpgIMG_5887.jpg
 
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mheimer_45

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Does your once fired brass have any primers left? I’m guessing your blowing primers and that’s why it’s so dirty
 

x2cross

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    Yep, 100% the primer cup. Look at the primers in the cases you've already fired. They'll have the center punched out. I had this problem with the supposedly high pressure Toolcraft bolt in my 6.5 AR10. I switched to the high pressure JP bolt, and the problem went away
     

    msgriff

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    It would help if you would list some details on the barrel mfg., length, gas system length and gas port diameter if you can. Also the BCG mfg, and model.
    With that many pierced primers, your bolt and firing pin might be toast, but I would still clean it up and check headspace with a field gauge. I would also measure the firing pin protrusion, pin tip diameter and the diameter of the bolt's pin orifice. I would imagine there is gas cutting damage, so the measurements might just be a post mortem.
     

    BuildingConceptsllc

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    Dang bro, you didn't notice the primers popping? How many rounds did you shoot?
     

    wade2big

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    Yep, 100% the primer cup. Look at the primers in the cases you've already fired. They'll have the center punched out. I had this problem with the supposedly high pressure Toolcraft bolt in my 6.5 AR10. I switched to the high pressure JP bolt, and the problem went away
    Was it the double ejector Toolcraft bolt? Those are the high pressure small firing pin bolts. I use them with no issues.
     

    FCS

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    You are piercing primers. If you have 15 pieces that came out of BCG, high probability you’ll have etched / damaged tip of firing pin, will need to be replaced to prevent continued piercing of primers.
     

    SargeB

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    Does your once fired brass have any primers left? I’m guessing your blowing primers and that’s why it’s so dirty
    The is a little hole in it about the size of the little metal shaving i posted. I cannot run anything thru the little hole on the spent brass primer.
     

    BuildingConceptsllc

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    I did not, the rifle performed fine until it didn't. And I fired at least at least 15.
    Well, I guess I am just used to looking at my brass all the time. If you didn't and the gun ran fine then I can see that.

    Definitely check out your bolt and firing pin situation. They may be fine but they may have some damage. Need to figure out why that happens of course. There are several here that are legit experts at AR's and can definitely get to the bottom of it with you.
     

    BuildingConceptsllc

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    The is a little hole in it about the size of the little metal shaving i posted. I cannot run anything thru the little hole on the spent brass primer.
    Can you post some pics of the bolt and FP and the brass?
     

    SargeB

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    Well, I guess I am just used to looking at my brass all the time. If you didn't and the gun ran fine then I can see that.

    Definitely check out your bolt and firing pin situation. They may be fine but they may have some damage. Need to figure out why that happens of course. There are several here that are legit experts at AR's and can definitely get to the bottom of it with you.
    I bet I do too in the future.....in MANY years shooting this is new to me.
     

    BuildingConceptsllc

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    I'm interested to see what it looks like. I think I've only ever popped a primer once myself, and that was with an overcharged or messed up factory round that they recalled. That was also a lot more than just a popped primer, came close to blowing my rifle up.

    It's a good practice to check the brass for pressure signs the first couple of rounds, but I had always assume factory ammo to be "no risk" but that really just isn't thr case. Good learning experience without any serious outcomes. Hopefully your bolt and fp is OK, be interested to see that and the brass when you get a chance.
     

    wade2big

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    I'm interested to see what it looks like. I think I've only ever popped a primer once myself, and that was with an overcharged or messed up factory round that they recalled. That was also a lot more than just a popped primer, came close to blowing my rifle up.

    It's a good practice to check the brass for pressure signs the first couple of rounds, but I had always assume factory ammo to be "no risk" but that really just isn't thr case. Good learning experience without any serious outcomes. Hopefully your bolt and fp is OK, be interested to see that and the brass when you get a chance.
    A friend gave me a whole bunch of once fired brass from his 6.5cm large frame. There were some nickel plated federal that didn’t play well with his rifle. He never knew he was piercing primers. The hole doesn’t go all the way through the primer.
    7D9EAA2A-4D3E-4582-8622-4E4F5DC72E40.jpeg
     

    whatsupdoc

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    This is not popping primers, popping primers is when the primer has been removed from the case.
    This is the firing pin piercing the primer and the pressure pushing the punched out primer cup "disk" back into
    the bolt.

    Not worth the time and aggravation, get a new bolt and firing pin or a entire BCG.
     

    Wile_Coyote

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    The timing in your AR10 is off. A high pressure bolt from JP or RCA will help. Slowing the cycle would probably stop the piercing. Gas and or buffer (weight and/or spring) are what to focus on.

    My 6mm Creedmoor did that constantly. One of my 6.5 Creedmoor’s did as well. Pierced primers occurred with factory ammo and custom. Common responses were “pressure, back of power charge and try again…”. The part missed was the powder charge was the lowest on the table.

    HP bolt didn’t stop it by itself. The addition of an adjustable gas block, H2 buffer and a stiff spring did. Runs like a clock now with no pressure signs, no pierced primers either.

    ETA: experience from this
     

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    Rocketvapor

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    It may take a magnifying glass or camera with macro capability to see the pin/bolt face damage.
    That many cookie cutter pieces in the bolt and the tip just has to be all cut up.
    Once the tip is damaged it will pierce every primer (until it burns away).
    Yes, we would like to see a pic.
     

    SargeB

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    I'm interested to see what it looks like. I think I've only ever popped a primer once myself, and that was with an overcharged or messed up factory round that they recalled. That was also a lot more than just a popped primer, came close to blowing my rifle up.

    It's a good practice to check the brass for pressure signs the first couple of rounds, but I had always assume factory ammo to be "no risk" but that really just isn't thr case. Good learning experience without any serious outcomes. Hopefully your bolt and fp is OK, be interested to see that and the brass when you get a chance.
     

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    SargeB

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    It may take a magnifying glass or camera with macro capability to see the pin/bolt face damage.
    That many cookie cutter pieces in the bolt and the tip just has to be all cut up.
    Once the tip is damaged it will pierce every primer (until it burns away).
    Yes, we would like to see a pic.
    I posted a pix. I reviewed the firing pin under a lighted magnifying glass and it shows no signs nor can my fingers discern any anomalies.
     
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    SargeB

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    The timing in your AR10 is off. A high pressure bolt from JP or RCA will help. Slowing the cycle would probably stop the piercing. Gas and or buffer (weight and/or spring) are what to focus on.

    My 6mm Creedmoor did that constantly. One of my 6.5 Creedmoor’s did as well. Pierced primers occurred with factory ammo and custom. Common responses were “pressure, back of power charge and try again…”. The part missed was the powder charge was the lowest on the table.

    HP bolt didn’t stop it by itself. The addition of an adjustable gas block, H2 buffer and a stiff spring did. Runs like a clock now with no pressure signs, no pierced primers either.

    ETA: experience from this
    I put an adjustable block on and fired at least 20 rounds yesterday......reviewing each spent case. I saw no popped primers. Going back today.
     

    SargeB

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    The timing in your AR10 is off. A high pressure bolt from JP or RCA will help. Slowing the cycle would probably stop the piercing. Gas and or buffer (weight and/or spring) are what to focus on.

    My 6mm Creedmoor did that constantly. One of my 6.5 Creedmoor’s did as well. Pierced primers occurred with factory ammo and custom. Common responses were “pressure, back of power charge and try again…”. The part missed was the powder charge was the lowest on the table.

    HP bolt didn’t stop it by itself. The addition of an adjustable gas block, H2 buffer and a stiff spring did. Runs like a clock now with no pressure signs, no pierced primers either.

    ETA: experience from this
    I put an adjustable block on and fired at least 20 rounds yesterday......reviewing each spent case. I saw no popped primers. Going back today.
     
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    Wile_Coyote

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    I put an adjustable block on and fired at least 20 rounds yesterday......reviewing each spent case. I saw no popped primers. Going back today.
    Good deal, hopefully just the adjustable gas block works for you. That is all one of my 6.5’s needed.

    Good luck and keep us posted 👍
     

    roostercogburn98

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    Your fingernail doesn’t drag on this area? It looks rough in the pic
    16B99A7F-165E-4F5B-8611-7A340C468FD8.jpeg
     

    Lawless

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    Is it a Vltor type/length receiver extension? Uses standard (3.25”)AR15 buffers?

    This may not cure the pierced primers but an H2 buffer and a Tubbs AR10 flat wire spring will help slow it all down and unlike “heavy” springs it won’t hurt reliability.
     

    SargeB

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    Strangely today as I would test fire and adjust the gas to allow for proper action, it would fire Hornady 80971 ok as I was ramping up the gas......once I got the gas tuned to work the action properly....it would eject spent rounds.....strip and feed the next round....lock the bolt open on the empty magazine.....this worked for other ammo without popping the primer but would consistently pop the primer on all the Hornady rounds....
     

    SargeB

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    Is it a Vltor type/length receiver extension? Uses standard (3.25”)AR15 buffers?

    This may not cure the pierced primers but an H2 buffer and a Tubbs AR10 flat wire spring will help slow it all down and unlike “heavy” springs it won’t hurt reliability.
    I appreciate the input, and may have to consider this
     

    Wile_Coyote

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    Strangely today as I would test fire and adjust the gas to allow for proper action, it would fire Hornady 80971 ok as I was ramping up the gas......once I got the gas tuned to work the action properly....it would eject spent rounds.....strip and feed the next round....lock the bolt open on the empty magazine.....this worked for other ammo without popping the primer but would consistently pop the primer on all the Hornady rounds....
    Same behavior mine had.
     

    FLIGHT762

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    I used an early production SR-25 from the late 90's to the early 2000's on a tactical team. I used Federal 168 GMM for years in it. Hornady came out with their new 168 AMAX TAP ammo. It shot well and I bought a couple of cases. After using up those lots of ammo, I bought the same new TAP replacement ammo. My rifle had a number of primers blanking and popping with the new stuff.

    I got ahold of Hornady L/E division. They had me send the ammo back for their testing. After a few months, I received some new ammo from to test. That 168 TAP ammo worked fine. I don't know what they tweaked, but the newest mfg. ammo worked fine.

    I eventually put a Tubbs flat wire spring and one of his Carrier Weight System (no longer available) Luckily, I bought two sets at the time.

    These gas guns get finicky. When reloading for them, (SR-25 & a 2013 GAP 10) I drop the powder charges 1-2 grains from my bolt gun loads otherwise the gas guns will beat the crap out of the brass.
     
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    Lawless

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    I appreciate the input, and may have to consider this
    Larue has them cheaper than Tubbs. Watch David Tubbs talk about the spring in his video and you’ll understand how it works.
     

    Wile_Coyote

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    Mine are running XLR stocks, so carbine length tubes. The Rainer barreled rifle eats anything suppressed or not with gas on an SLR gas block open 5 clicks. Rifle length gas. JP SCS configured H2. Full mass carrier, even without a HP bolt never had a problem. Groups great. factory and custom ammo.

    The proof barreled rifle, pierced primers just like the OP’s even with an HP bolt from JP and RCA. It had a SCS configured H2 same XLR stock, full mass carrier. Rifle +2 gas. Swapped the spring to the heavy that came with the SCS and never another problem. Eats everything suppressed and not and is grouping great although I still have load work to do. Factory and custom ammo no problems.

    Now that proof mentioned above, was barreled for 6mm Creedmoor until very recently. It pierced primers on everything after the first 30 rounds of it life but. Eroded a standard bolt and actually broke a JP titanium firing pin in a JP HP bolt. Only thing I didn’t try was swapping that spring. Had the H2 SCS, SLR adjustable gas block, full mass carrier and rifle length gas.

    Got tired of dealing with it and pulled the barrel off and replaced it with a 6.5. Shame the 6mm was nice when it was shooting. Ehh well maybe one day I will buy another upper and try the barrel again with the configuration I mentioned.

    The heavier spring was the key on my SCS. Brass is ejected and not beat, no swipes, no cratering.