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Case head separation with factory ammo


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First off, I have done a search and cannot find an answer to my particular set of problems.  I shot a match yesterday and had case head separations.  After doing research last night, I thought that I may have had some bad brass or some brass that had the "glock" bulge or stepped brass in my reloads.  I then went and purchased UMC 9mm 115gr ammo and went to the range this morning and had a case head separation on my first shot. This is making me nervous so I bagged up my gun and came home.  Also, with all of my case head separations, I have had the bullet get stuck in the barrel.  They are usually just a couple of inches in the barrel, but the one this morning is in the middle of the barrel.  I haven't had a chance to push it out yet, but that is what I will be doing when I finish this post.  

 

Here are specs on my rifle:

 

Gibbz Arms g9 lower https://gibbzarms.com/product/g9-lower-receiver/

Gibbz Arms g9upper https://gibbzarms.com/product/g49-side-charging-upper-receiver/

Gibbz arms g9 9mm pcc bolt https://gibbzarms.com/product/ambi-9mm-pistol-caliber-ar-bolt/

Gibbz arms gen 2 15" ultra Lite  handguard 

Barrel - YHM 16.5" 9mm barrel non chrome YHM-90-T

Comp - YHM-85-MB-A Slant brake comp 

Lower Parts Kit - Armaspec Lower Parts Kit

Trigger - Elftman Tactical AR9 Trigger

Stock - Magpul CTR Stock

 

A little history on the gun - 

 I put this together almost a month ago.  Took it out and shot it.  After about 217 rounds I saw that the trap door on the back of the upper receiver was damaged.  I shipped it back to Gibbz and it turns out I had an out of spec buffer tube.  Luckily I ordered the buffer, tube, and spring from Gibbz, so they replaced the damaged parts and the out of spec buffer tube and also put a longer buffer in.  They fired 20 test rounds and sent it back to me.  I went out Thursday evening and shot about 300 rounds through it and I had one case head separation somewhere around the 275 round mark.  I didn't think anything of it and just figured it was a fluke and after the tens of thousands of rounds of 9mm I have reloaded and not had one, I just figured I missed a piece of brass in my reloading process.   Yesterday I shoot the match and have one on the first stage about 18 rounds in.  (I cleaned the rifle after shooting Thursday.)  I went to the safe area and cleaned out the brass and the dislodged bullet and continued to shoot.  On the last stage of the day about 7 shots in, I had the same thing happen although this time no bullet was lodged in the barrel.  I took it home last night, cleaned it, did a bunch of research and figured I had some stepped cases.  I went to the LGS and bought 250 rounds of UMC and went to the range this morning for a steel challenge match. I figured before I started I would shoot a few magazines and see if I have any issues and on the first round fired, I had the same issue.  I packed it up and figured that I would come back and do some more research.  At this point in time, I feel like I have been playing with fire and am wondering how many more times I can do this before the gun blows up on me.

 

Here are my reloading specs:

Case: range pick up brass

Primer: Federal small pistol primer

Powder: 5.4 grains of unique

Bullet: 115Gr Berry's bullet

COAL: 1.141

 

I have fired tens of thousands of this load through multiple different pistols and never had an issue. After doing some research, I think that I need to sort out any stepped brass that I may have in these loads and throw them away because I have probably gotten lucky. 

 

 

 

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Hello: Check to see if your firing pin spring is broken or the firing pin is tight in the bore. That one looks like a slam fire, out of battery ignition to me. I would also drop a round in the barrel to make sure you don't have a piece of a two piece case in the chamber. Thanks, Eric

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Really confused why you'd have a bullet lodged in the barrel  ????

 

Or, why factory ammo would have insufficient powder to blow

the bullet out the barrel  ????

 

The rest of it, as others have mentioned, sounds like the gun

was "out of battery"  ….   but, why a bullet in the barrel ?

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4 minutes ago, Hi-Power Jack said:

Really confused why you'd have a bullet lodged in the barrel  ????

 

Or, why factory ammo would have insufficient powder to blow

the bullet out the barrel  ????

 

The rest of it, as others have mentioned, sounds like the gun

was "out of battery"  ….   but, why a bullet in the barrel ?

Not sure, but was able to push it out the rest of the way quite easily with a 1/4" wooden dowel from the chamber side.  The bigger issue is why is the trigger able to be engaged and strike the firing pin when the bolt isn't closed all the way, and then how do I fix it?  Heavier buffer spring? 

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5 minutes ago, Hi-Power Jack said:

Really confused why you'd have a bullet lodged in the barrel  ????

 

Or, why factory ammo would have insufficient powder to blow

the bullet out the barrel  ????

 

The rest of it, as others have mentioned, sounds like the gun

was "out of battery"  ….   but, why a bullet in the barrel ?

Well, if a gun is out of battery just a little like the video shows I could see the bullet moving down the he bore a little while the majority of the pressure gets vented out the back.

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2 hours ago, Steve RA said:

Seems like the bolt may be opening too early.  Check everything back of the bolt as you could have a broken spring or some other problem.

 

Steve is correct. This would be the fist place I would look.

Remove your bolt and buffer and weigh them together. The weight (bolt plus buffer) should be as close to 20 ounces as you can get and if it comes out a little heavier than that, so much the better.

 

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1 hour ago, Sarge said:

if a gun is out of battery, I could see the bullet moving down the he bore a little while the majority of the pressure gets vented out the back.

 

Guess so, but the three case separations I had, the bullets all exited the barrel ...

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4 hours ago, Jeremyc_1999 said:

Lower Parts Kit - Armaspec Lower Parts Kit

 

3 hours ago, Jeremyc_1999 said:

I checked the buffer and spring and everything looks okay 

 

First thing I'd try would be a heavier spring, and see if that gets it into battery.  

 

Standard AR-15 buffer and spring are usually way too light for a blowback 9mm.  I run a 7.5 oz buffer and AR-10 carbine spring.

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1 hour ago, sixsixnine said:

 

 

First thing I'd try would be a heavier spring, and see if that gets it into battery.  

 

Standard AR-15 buffer and spring are usually way too light for a blowback 9mm.  I run a 7.5 oz buffer and AR-10 carbine spring.

Not even close to being true,

That used to be the standard set up in Colt machine guns back in the day!

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19 minutes ago, Jeremyc_1999 said:

Should the gun be able to fire when it is out of Battery?  I can try a heavier spring if that is the solution, but I guess I’m still concerned about the gun firing with the gun out of battery 

Check for hard crud build up where the bolt face meets the barrel face. It will look like a ring around where the barrel seats in the receiver.

Might be enough to keep the bolt from fully closing and give you a out of battery problem.

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11 minutes ago, dmshozer1 said:

Check for hard crud build up where the bolt face meets the barrel face. It will look like a ring around where the barrel seats in the receiver.

Might be enough to keep the bolt from fully closing and give you a out of battery problem.

the bolt is immaculate.  The most that the gun has had fired between thorough cleanings is 275 rounds. The firing pin moves forward and back freely.  If you look at my video here: https://imgur.com/gallery/zEh4aZ1 I was able to keep hold of the bolt to keep it from fully closing to demonstrate that the trigger will engage the firing pin with it being out of battery.  

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2 hours ago, Jeremyc_1999 said:

Should the gun be able to fire when it is out of Battery?  I can try a heavier spring if that is the solution, but I guess I’m still concerned about the gun firing with the gun out of battery 

 

To me the video you posted shows normal operation of an AR. It shouldn't be firing out of battery even when it's dropping the hammer on the bolt carrier like that tho (if you did the same thing with a live round on the bolt face). I'm not 100% on this though and if someone else could share, it would be helpful. 

 

I think you have a headspace problem or a bad chamber 

 

 

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