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1/22/2020 12:12:56 PM
Posted: 1/18/2015 10:31:18 AM EST
[Last Edit: 1/18/2015 10:32:25 AM EST by AlamTX]
This is a friend of mine's Bushmaster 16 inch with a carbine length gas tube. It's a standard configuration and nothing has been modified by him. He told me that he got to fire one round and then this happened. He didn't take the gun to the range after that. I figured maybe it was an extractor issue so I had him bring it over and I replaced the extractor spring and put in a BCM extractor upgrade with the beefier spring and O ring, etc.

He took it to the range and said the same thing happened again. It looks like the extractor is ripping the rim of the cartridge off, but the case is still stuck in the chamber. He sent a couple of pictures to me. He mentioned that maybe he should replace the whole BCG, but if it's a different issue, then he just wasted a hundred bucks. He's been using American Eagle 5.56 ammo.

What do you think it could be?


Link Posted: 1/18/2015 10:37:54 AM EST
Could be a manufacturer error, port too small. Not getting enough gas to cycle properly.
Link Posted: 1/18/2015 10:39:03 AM EST
If the spent casing can be removed, clean the chamber.

Did he clean the chamber before he first fired it?

Also, hard to tell, but it looks like there are rough chamber markings on the spent casing in the photos.
Link Posted: 1/18/2015 10:50:13 AM EST
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Originally Posted By KBAD:
If the spent casing can be removed, clean the chamber.

Did he clean the chamber before he first fired it?

Also, hard to tell, but it looks like there are rough chamber markings on the spent casing in the photos.
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You think the chamber can be that dirty on a brand new firearm? Dirty, I can understand but dirty enough to have the case jammed in there so hard that the extractor rips the rim off?


Link Posted: 1/18/2015 11:05:46 AM EST
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Originally Posted By AlamTX:
You think the chamber can be that dirty on a brand new firearm? Dirty, I can understand but dirty enough to have the case jammed in there so hard that the extractor rips the rim off?


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Originally Posted By AlamTX:
Originally Posted By KBAD:
If the spent casing can be removed, clean the chamber.

Did he clean the chamber before he first fired it?

Also, hard to tell, but it looks like there are rough chamber markings on the spent casing in the photos.
You think the chamber can be that dirty on a brand new firearm? Dirty, I can understand but dirty enough to have the case jammed in there so hard that the extractor rips the rim off?





KBAD was trying to point out that the fired case looks like it has a ring imprinted on it from a crappy chamber, not that the chamber was dirty. need a better picture of the fired case, side shot, no shadows please.
Link Posted: 1/18/2015 11:14:12 AM EST
Looks like it is trying to extract while cartridge is still stuck to chamber.(Over-gassing)JMHO
Link Posted: 1/18/2015 11:16:38 AM EST
Many rifles are shipped with a rust preventative coating that is very tacky, and will cause problems with extraction. It needs to be removed. Some CLP on a GI chamber brush followed by patches would do the trick.
Link Posted: 1/18/2015 11:42:50 AM EST
If the chamber brush doesn't do the trick, then it would be a gassing issue?

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Link Posted: 1/18/2015 11:45:22 AM EST
Correct. Polishing the chamber is the first easy step, generally.
Link Posted: 1/18/2015 11:48:05 AM EST
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.
Link Posted: 1/18/2015 11:50:08 AM EST
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Originally Posted By SandWMandP15Tee:
Could be a manufacturer error, port too small. Not getting enough gas to cycle properly.
View Quote


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.
Link Posted: 1/18/2015 11:51:12 AM EST
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Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.
View Quote


NO!
Link Posted: 1/18/2015 11:55:05 AM EST
Sounds like a timing issue, if polishing the chamber doesnt work.
Link Posted: 1/18/2015 11:56:33 AM EST
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Originally Posted By StevenH:


NO!
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Originally Posted By StevenH:
Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.


NO!
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.


Link Posted: 1/18/2015 11:59:10 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.
View Quote


After I replaced the extractor spring, I did cycle it several times and the rounds ejected just fine. I did fire or six in a row at a time a few times. That's what makes me wonder about the chamber.

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Link Posted: 1/18/2015 12:00:10 PM EST
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Originally Posted By KBAD:
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.


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Originally Posted By KBAD:
Originally Posted By StevenH:
Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.


NO!
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.




Roger.

I wasn't thinking of doing that, though.

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Link Posted: 1/18/2015 12:03:59 PM EST
What fixed my bushmasters (that used to fail to extract with M193 in hot weather) was opening the throat with a Michiguns chamber reamer.
Link Posted: 1/18/2015 12:13:07 PM EST
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Originally Posted By StevenH:


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.
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Originally Posted By StevenH:
Originally Posted By SandWMandP15Tee:
Could be a manufacturer error, port too small. Not getting enough gas to cycle properly.


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.


You mean they shipped a .223 and labeled it a 5.56?


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Link Posted: 1/18/2015 1:01:43 PM EST
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Originally Posted By AlamTX:


You mean they shipped a .223 and labeled it a 5.56?


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Originally Posted By AlamTX:
Originally Posted By StevenH:
Originally Posted By SandWMandP15Tee:
Could be a manufacturer error, port too small. Not getting enough gas to cycle properly.


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.


You mean they shipped a .223 and labeled it a 5.56?


Posted Via AR15.Com Mobile


Very common.

If you "trust" the markings on the bbl then that trust is based on many assumptions. First that the seller even knows the difference and cares. Second that the company that cut the chamber knows the difference and cares. Third that if the company that cut the chamber knows and cares and used a sharp 5.56mm reamer that still cuts a true 5.56mm chamber. Not a worn or dull one that no longer cuuts a proper 5.56mm chamber.

I "trust" Colt, BCM & LMT to ship with a true 5.56mm chamber. Ive had enough "bad" Bushmaster Bbls that I bought my own Michiguns reamer.

You can always call Bushmaster and ask them to explain the differences between a 5.56mm vs .223 chamber and throat and what steps they take to ensure a true 5.56mm chamber and throat during chambering and to verify after chambering. The answer might impress you or terrify you depending on who you speak to and their willingess to answer.
Link Posted: 1/18/2015 1:23:50 PM EST
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Originally Posted By AlamTX:
You think the chamber can be that dirty on a brand new firearm? Dirty, I can understand but dirty enough to have the case jammed in there so hard that the extractor rips the rim off?


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Originally Posted By AlamTX:
Originally Posted By KBAD:
If the spent casing can be removed, clean the chamber.

Did he clean the chamber before he first fired it?

Also, hard to tell, but it looks like there are rough chamber markings on the spent casing in the photos.
You think the chamber can be that dirty on a brand new firearm? Dirty, I can understand but dirty enough to have the case jammed in there so hard that the extractor rips the rim off?




Yes clean the chamber. I was talking with one of our best 1911 smiths last week about 1911 malfunctions. We both agreed that it's due to the operator not knowing what to do and how he firearm functions. Not everything is "out of spec". Take the gun apart, clean then try it.
Link Posted: 1/18/2015 3:33:57 PM EST
Link Posted: 1/18/2015 4:02:25 PM EST
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Originally Posted By KBAD:
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.
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Originally Posted By KBAD:
Originally Posted By StevenH:
Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.


NO!
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.


Good point, never thought about that.
Link Posted: 1/18/2015 4:06:34 PM EST
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Originally Posted By heavily_armed:


Good point, never thought about that.
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Originally Posted By heavily_armed:
Originally Posted By KBAD:
Originally Posted By StevenH:
Originally Posted By heavily_armed:
As previous guys suggested, there may be crud in the chamber, or it may have a burr. With rifle pointed in safe direction (preferably at a range), manually cycle rounds by loading a full mag and pulling charging handle all the way back and letting it fly. Do this a few times. Remove firing pin if you want to reduce chance of ND. If rounds cycle smoothly, problem is likely in gas system.


NO!
do not remove firing pin as StevenH said. You could get BCG stuck in upper if cam is allowed to rotate without the firing pin installed.


Good point, never thought about that.

It will stick in there like a bastard.

A short firing pin is a good tool to have on hand.
Link Posted: 1/18/2015 5:56:13 PM EST
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Originally Posted By StevenH:


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By StevenH:
Originally Posted By SandWMandP15Tee:
Could be a manufacturer error, port too small. Not getting enough gas to cycle properly.


Please dont give sarcastic answers to tech forum posts.

carbine may be over gassed or it may not have a true 5.56mm chamber and throat. Or it may be a combo of both like a couple of bushmasters I own.
Wasn't being sarcastic.
Link Posted: 1/18/2015 7:13:29 PM EST
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Originally Posted By vbfg135:
Looks like it is trying to extract while cartridge is still stuck to chamber.(Over-gassing)JMHO
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My guess also
Link Posted: 1/18/2015 8:25:36 PM EST
As has been suggested , always start with the simple stuff . Clean the chamber like a demon and inspect the used brass .

Could be as simple as grit in the chamber "grabbing" the brass . Might have a rough spot or two in the chamber that will work itself smooth

with a bit of shooting if the chamber is kept clean.

Might be a chamber that is cut poorly that will never fix itself.


The way I am reading this is a fairly new factory gun? Right? If so clean , lube and continue to shoot. If it still is doing that after 2 or 300 rounds contact whoever built it
Link Posted: 1/18/2015 10:07:59 PM EST
Photos not show markings on the brass very well.

But the brass casing looks like a reload to me. It's too marked up and dirty to be a virgin empty.

The crimp at the primer is the giveaway. Yes, you can see the remain of an old crimp ring on the brass, but it is not holding the current primer in.

I'd be worried about the rounds being improperly manufactured reloaded rounds. The primer isn't showing signs of overpressure, but the markings on the casing and the rim being ripped off are signs of too much pressure.
Link Posted: 1/18/2015 11:35:30 PM EST
[Last Edit: 1/18/2015 11:35:47 PM EST by sully]
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