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My neighbor just bought a DPMS SASS LR-308 and he and I went shooting the last two days.  His gun ran fine yesterday until the end of the shooting session when it started having stovepipes (failures to fully eject the case; the bolt is cycling far enough to strip the next round from the magazine though).  I suggested that he clean it thoroughly and then lube it generously and then we'd take it out again to see if the problem went away.  Fast forward to today and we went shooting again and the problem persisted.  The malfunctions were all the same; he never had failures of any other kind.  Ammo was German FMJ ("MEN" headstamp) and the magazines were the two metal 20-rounders that come with the gun from DPMS.

His rifle has the stubby buffer that is shorter than an M4 (5.56mm) buffer and my first thought was that maybe this buffer didn't provide enough mass for reliable cycling?  That's just a guess though.  Any suggestions that I could relay to my neighbor?  He's really thrilled with the accuracy of the rifle and he really wants to get it cycling reliably.

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If it ran fine yesterday, it's not the buffer...

Did he clean it?  You suggested it, but did he do it? 

How long has he had this rifle, and how much has he shot it?  Need more background info to see what's up. 

Might just be a broken ejector, or ejector spring...  details, man, details...

Edited by 98Z5V

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He said he cleaned it; maybe I should see what his definition of that is!

He bought it just a few weeks back and he shot it for the first time with me.  All ammo was that German "MEN"-stamped FMJ.  He shot about 300 rounds of that stuff through it, max.

The bolt was locking back on the last round in the mag.  The only malf that he encountered was that stovepipe-cum-double feed.

I'll ask him to let me take a look at it as I have more experience with the AR (albeit in its 5.56mm guise) and I could probably spot something amiss more readily than he.

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If this is a new weapon there is a good chance some of the extra brass shavings they produce till smoothed out could be messing with the ejector. Totally disassemble, inspect, and clean.

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Are you sure the malfunction happened with both magazines? Though it doesn't sound like a mag issue. Check to see if the ejector spring is intact. Not familiar with the DPMS factory bolt, but if it has a rubber donut gasket under the ejector spring, make sure that isn't split. That caused a similar problem in my Armalite AR10T. Replaced it runs fine now.

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1 hour ago, Sisco said:

Are you sure the malfunction happened with both magazines? Though it doesn't sound like a mag issue. Check to see if the ejector spring is intact. Not familiar with the DPMS factory bolt, but if it has a rubber donut gasket under the ejector spring, make sure that isn't split. That caused a similar problem in my Armalite AR10T. Replaced it runs fine now.

Pretty sure that's an ar-10 thing

 

also herk make sure he's lubing it good, more than a regular rifle, like twice as much. Wet wet wet. 

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First, thanks for everyone who replied!  Very helpful.

Secondly, I saw my neighbor this evening and he did NOT clean the rifle.  I walked him through that and got him to lube it too.  Next time we go shooting, I'll make sure that he shoots more than one brand of ammo.  Also, I'll bring some Magpul magazines to try, in case the metal magazines are part of the problem.

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On 4/24/2017 at 7:41 PM, Sisco said:

Are you sure the malfunction happened with both magazines? Though it doesn't sound like a mag issue. Check to see if the ejector spring is intact. Not familiar with the DPMS factory bolt, but if it has a rubber donut gasket under the ejector spring, make sure that isn't split. That caused a similar problem in my Armalite AR10T. Replaced it runs fine now.

I am reasonably sure that I had him try both magazines, as I am a "blame ammo and mags for malfunctions first and everything else second" kind of guy.  I also remember him switching magazines while I watched and he still got the same malf.

There was no rubber donut gasket on his extractor spring so I gave him one tonight and helped him install it.  My KAK .308 BCG takes two of these gaskets but the DPMS didn't seem to want to go back together with two.

The extractor spring isn't tapered like most that I've seen and it would just fall out if the extractor was turned upside down.  Is that just how the DPMS .308 extractor springs are?

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1 hour ago, Herk308 said:

I am reasonably sure that I had him try both magazines, as I am a "blame ammo and mags for malfunctions first and everything else second" kind of guy.  I also remember him switching magazines while I watched and he still got the same malf.

There was no rubber donut gasket on his extractor spring so I gave him one tonight and helped him install it.  My KAK .308 BCG takes two of these gaskets but the DPMS didn't seem to want to go back together with two.

The extractor spring isn't tapered like most that I've seen and it would just fall out if the extractor was turned upside down.  Is that just how the DPMS .308 extractor springs are?

I think there's some confusion going on in this thread on "Extractor vs. Ejector." 

I think this rifle might have a broken ejector or ejector spring.  The rounds are being pulled out of the hot chamber - so the extractor is working.  They're not getting thrown out of the ejection port, so something is stopping the ejection of the spent case.

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    DPMS LR 308's have a two Spring Extractor Spring , on fits inside the other . Should not need a Donut or O-ring . Too much Spring pressure on the Extractor or a Extractor with a Burr or too much hook , can hold on to the fired Case too long & cause an issue like this .

     I had a D. Wilson that was doing the same thing & the first thing I did was clean & inspect & finding nothing wrong , issue still was there , upon changing the Extractor , issue went away . 
 The Ejector can also cause the same issue if its Spring is weak or its hanging up or restricted from normal movement. I have seen short Ejector Springs do the same thing .   . Also a dirty or rough Chamber can also cause this issue , not to mention , Ammo .

 Was the Ejector disassembled & cleaned & inspected , as was brought up earlier in this Thread ? You can Change one Component system at a time to see if it goes away .

 Being a new Rifle means nothing anymore , most are mass produced & out sourced components can show up bad in any Rifle .

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11 hours ago, 98Z5V said:

I think there's some confusion going on in this thread on "Extractor vs. Ejector." 

I think this rifle might have a broken ejector or ejector spring.  The rounds are being pulled out of the hot chamber - so the extractor is working.  They're not getting thrown out of the ejection port, so something is stopping the ejection of the spent case.

your right my mistake

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I did not remove the ejector.  I did test the ejector by taking the bolt and clipping a live cartridge under the extractor and then pressing it down onto the bolt face, compressing the ejector.  When I removed thumb pressure from the cartridge, the ejector flung the round away.  I don't know if that really tells us anything, but there is at least a little happening with the ejector.

If I strip the ejector from the bolt will it be obvious what I'm looking for?  Is there a certain length that the spring should be?

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1 hour ago, Herk308 said:

I did not remove the ejector.  I did test the ejector by taking the bolt and clipping a live cartridge under the extractor and then pressing it down onto the bolt face, compressing the ejector.  When I removed thumb pressure from the cartridge, the ejector flung the round away.  I don't know if that really tells us anything, but there is at least a little happening with the ejector.

If I strip the ejector from the bolt will it be obvious what I'm looking for?  Is there a certain length that the spring should be?

You'll either pull out a 2-piece ejector, or a 2-piece ejector spring...

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On 4/26/2017 at 5:57 PM, 98Z5V said:

You'll either pull out a 2-piece ejector, or a 2-piece ejector spring...

Actually both were one-piece designs.  Does he have the incorrect parts?

I took measurements of the ejector and they are as follows:

Length: 0.574"

Large/Main Diameter: 0.151"

Small Diameter: 0.080"

Spring OAL (extended): 0.880"

No measurement was taken of the compressed spring.

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Nope, I was betting that the ejector or ejector spring were broken, thus two pieces each...  If they were intact, then I made the wrong bet...

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On 4/25/2017 at 10:03 PM, Herk308 said:

First, thanks for everyone who replied!  Very helpful.

Secondly, I saw my neighbor this evening and he did NOT clean the rifle.  I walked him through that and got him to lube it too.  Next time we go shooting, I'll make sure that he shoots more than one brand of ammo.  Also, I'll bring some Magpul magazines to try, in case the metal magazines are part of the problem.

Think you need to go back to this and the only good liberal thing is applying oil "liberally". Give is a good bath let it soak in for a day or so, use a synthetic it'll fill all the nooks and crannies!!

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Below is a photo of a DPMS LR 308AR Extractor spring set ,small one fits into the large one , of course ., next to an AR 15 one . Even my D.Wilson & SI Defense , use the same spring set up . A donut O-ring might help , but hard to say till you try it & since I have not seen in your posts that he has yet . This is a LR version & not a G2 correct .

  I will measure the extra new Ejector Springs I have to compare .One thing you could do if you or another shooting friend had another complete Bolt , & just try it to see how it works . Though its not a good idea to use a already seated Bolt in another Barrel , just using it to test should not cause any issues . This will tell you the Bolt components are not the issue & to look at other things , like the Chamber being rough or wrong Buffer or Spring or even the gas system . 

DSCN2362.thumb.JPG.d62761e1e5643240c305f38cc44eff5a.JPG

 

Edited by survivalshop

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3 hours ago, survivalshop said:

Below is a photo of a DPMS LR 308AR Extractor spring set ,small one fits into the large one , of course ., next to an AR 15 one .

I seem to recall that my neighbor's extractor had a spring setup like that: small spring inside of a big one.  And yes, you are correct that this is the "normal" DPMS .308, not the G2.

I can't think of anyone else that I know who has a DPMS .308 bolt besides my KAK bolt with dual ejectors.  Should we test-fire with that one?

Edited by Herk308
Clarity

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9 hours ago, Herk308 said:

I can't think of anyone else that I know who has a DPMS .308 bolt besides my KAK bolt with dual ejectors.  Should we test-fire with that one?

  If its DPMS LR 308 compatible , yes , just to test . 

 I measured a bunch of Ejector Springs from D.Wilson & DPMS  , most were 0.950" , one was 0.920" & a well used DPMS with several thousand rounds through it , was 0.908 " all not compressed of course .  I would change the Ejector Spring first , if you need one , I can send you one of these , just PM me with an address & I snail mail it to you .

  D.Wilson has some nice kits available for Bolt Components also .

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11 hours ago, survivalshop said:

  if you need one , I can send you one of these 

Wow, that would be great!  Thank you.

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Took a while to get to the range since my neighbor works in HVAC and they are just now getting out of their busy season but @survivalshop sent me an ejector spring for my neighbor's rifle, free of change and I just want to publicly thank him for his generosity!  We installed the spring and went and shot about 200 rounds of German FMJ (the stuff with the "MEN" headstamp).  Previous to replacing that spring, my neighbor's rifle would work pretty well for the first part of the day but start stovepiping after a little while.  This time, there was a couple of stovepipes right away but they stopped after a bit of shooting.  Perhaps the spring had to 'break in' a bit?  I don't know if that's a thing but my neighbor wants to do another shooting session soon to test the rifle more.  It's encouraging that the stovepipes actually went away as he shot more.

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  Good to hear it did something , I have found with any AR model , they seem to be different in what fixes the extraction/ejection issues . I just had an old build , AR 15 that had weak ejection & the first thing I found after examining the components was a misshapen Buffer Spring , so it was the first thing I changed & it solved the hot brass landing on my hand .

    Sometimes its the Extractor or the Ejector , seems you have to try one or another to solve an issue . The Rough Chamber holding on to the Cartridge too long ( timing ) used to be a issue with early DPMS LR rifles , but not so much anymore. We have been seeing some Barrel Manufacturers using an incorrect Gas Port size in the Barrel ,causing issues .

   Keep her well lubricated & see how she works .

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