Jamming Issue, need some pointers

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Jamming Issue, need some pointers

Postby DrRock » Sat May 22, 2010 7:07 pm

I've got about 5 boxes through the gun. It sits on a CMMG lower and has a VLTOR Emod stock. I've been having this jamming issue since I got it. It always hangs the same way as in the pictures. Sometimes I'll get through a mag with no problem, sometimes 2 or 3 round bursts, but like clock-work, it will jam 5-6 rounds out of every box. Got it lubed up good. Any ideas on what may be causing it? It's almost like the casing are to big to fit out the ejection port. Thanks for any advice you fellas can give me Image Image . Image
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Re: Jamming Issue, need some pointers

Postby Hoot » Sat May 22, 2010 9:17 pm

From what I see in the pictures, it sure looks like the next round is riding too high and the spent brass is hanging up on it. Are you using a factory magazine or a standard 5.56 magazine? If the latter, you might want to tweak the lips a little tighter to hold the round a little lower.

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Re: Jamming Issue, need some pointers

Postby Siringo » Sat May 22, 2010 9:34 pm

Ejector stuck down or weak?
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Re: Jamming Issue, need some pointers

Postby gunnut » Sat May 22, 2010 9:59 pm

What buffer are you using? It looks like the bolt did not pick up the next round.
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Re: Jamming Issue, need some pointers

Postby BayouBob » Sun May 23, 2010 12:51 am

The ejection port looks right. Notice the front half of the port is milled a little larger than the rear? Like Hoot said it could be your magazine lips. On the other hand if the problem is something else a case hung in the action would keep the rear of the next round down while the front tries to ride up. Could be a weak ejector spring or a tiny bit of metal in the ejector hole. It could also be your gas port has something blocking it or is not perfectly aligned with the gas tube. I think though, if it was a gas pressure or buffer issue it would be more likely to eject but not pick up the next round. If you are handy with taking an AR apart you could check all those things. If not I'd email those pics to Bushmaster and see what they think.
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Re: Jamming Issue, need some pointers

Postby DrRock » Sun May 23, 2010 5:40 am

Thanks guys. The magazine is the one that arrived with the upper from BM. GunNut, the buffer is the standard one that came in the VLTOR Emod Combo Kit. I just checked their website and can't find anything that would identify the buffer by anything other than "buffer". I'm pretty sure the spent case is not getting out of the way of the next round. As soon as I pull out the spent case (the cases that hang are always scored on the sides) the bolt rides forward always picking up next round but of course does not have enough force to fully seat the round. I'm mechanically inclined but minimally experienced with the AR upper. Since it's been doing this out of the box, I should probably contact BM like suggested. I'll feel a little better about it knowing it may not be 100% user error.
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Re: Jamming Issue, need some pointers

Postby bushmeister » Sun May 23, 2010 6:53 am

In addition to what was suggested above, check to make sure your chamber is clean. It does look in the first picture like your magazine might be the problem though. Can you load a mag and take a pic of it outside of the gun?
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Re: Jamming Issue, need some pointers

Postby Siringo » Sun May 23, 2010 7:50 am

Also try this:

pull the bolt assembly out of the upper. Using one of your fired cases, put it into the front of the bolt and see if there is adequate tension on the ejector to fling it loose. You will need to insert the case under the extractor and rotate against the ejector.
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Re: Jamming Issue, need some pointers

Postby DrRock » Sun May 23, 2010 3:16 pm

Chamber is clean and as I mentioned, same problem from the day I bought it. Siringo, the ejector flips the casing about 4 or 5 feet and doesn't feel sloppy or anything. In the first picture of the post from yesterday that loaded round under the casing is being forced up and in by the bolt and is only stopped by the spent casing. Once the casing is pulled out the bolt and fresh round carry on their way...just not with enough force to fully seat. Here is some pics of the magazine fully loaded. It looks normal to me but its always looked this way. Image Image Image
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Re: Jamming Issue, need some pointers

Postby Siringo » Sun May 23, 2010 6:16 pm

Did they send you an aluminum mag? I thought they were all Stainless Steel.
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