First time shooting, FTF all day.

[sketch]

The new lips were a tad tall or the whole mag sat farther up in the action. His rings were worn from several k rnds. The bolt would also get wedged in the closed position with a live rnd in chamber. When he fired the first rnd it sounded and felt the same but ejected shorter by 3 feet in normal direction. Next rnd chambers click no boom stuck again. Mag was to tall :)

thanks. So is he having double feeds from the mags, or not ejecting the spend round? What was it about the lips that were wrong?

[Powerman]

Powerman we should go shooting!  My story is similar to yours and I have yet to find a solution.  I recently took my lower back to the Manufacturer and he ended up moving the pivot point for my bolt catch and replacing my lower parts kit.  He said that he doesn't know if that will affect the short stroke problem, but he fixed it none the less.  I also recently polished my chamber, but after watching a few youtube videos I used a slightly different method than the chamber brush listed above. 

 

One thing I'd like to try on the next outing:  I seem to recall getting through the 1st magazine successfully and the short stroke starts on Mag 2 or 3.  If this is really the case and not just my imagination; I thought that I could test the theory by letting the gun sit for a while after the 1st short stroke and/or bringing a can of compressed air to cool it off.  I think that this would point to a tight chamber (barrel heat, etc...).

 

My wife is expecting baby #2 any day.  As soon as things are back to normal around here, I'm going to hit the range an see if any of this crap worked!

 

Good luck buddy and you're not the only one!

 

ps: survivalshop,  Can you elaborate on the magazine catch?  I noticed that mine was looser (more screwed out) when I got it back from repair.  How does this affect the cycling and how tight should it be?

 

 

 

Congrats on the incoming! I have read your stuff too. It is irritating because it's just a mechanical object... replace non functioning part everything works fine. Silly to have to chase our tails around over something that seems simple on the surface. 

 

I really do not think I am short cycling. I do think that was my problem in the beginning due to not enough lube and break in, but I do not think that is going on now. I'm not an expert... all I am going on is consistent case placement before and after failures and my bolt is locking back on last round. Other than that, sure there can be more... I am having failures to eject right now, and that is the problem.

 

As far as a tight chamber... I sort of thought that the extractor would rip of the case and that I should see more damage on the case, but it does not seem bad at all. Nothing that I could not explain by just returning to battery on a fresh round. I thought a tight chamber would give you a fail to extract, which is not what I have. 

 

But I do suppose that it could require more force which would perhaps change things and even though it was extracted, that it could still come off the extractor and fail to eject. 

 

Here is a cool video I found on a failure to eject with high speed camera. the solution of course was to change extractor springs and all your problems go away... except mine didn't. 

 

Failure to eject

[Powerman]

The new lips were a tad tall or the whole mag sat farther up in the action. His rings were worn from several k rnds. The bolt would also get wedged in the closed position with a live rnd in chamber. When he fired the first rnd it sounded and felt the same but ejected shorter by 3 feet in normal direction. Next rnd chambers click no boom stuck again. Mag was to tall :)

 

Cool, thanks. I'll look at that stuff. Right now I numbered my mags. I think I will start using two old and two new... but I could not tell you how "old" my old ones are. I bought them beginning of last year, and the "new" ones in the middle... but they would certainly be from different lots.

[gsmopar]

I found this cool video on short stroking.  If I had to do this all over again, I would have bought a Ruger SR7.62.  I enjoyed the build, but I've spent too much time troubleshooting and not enough time shooting.

 

http://www.youtube.com/watch?v=bL808lxdEsA

[Powerman]

I found this cool video on short stroking.  If I had to do this all over again, I would have bought a Ruger SR7.62.  I enjoyed the build, but I've spent too much time troubleshooting and not enough time shooting.

 

http://www.youtube.com/watch?v=bL808lxdEsA

 

Nice. I'll have to take a closer look at my brass from last outing. Most was NATO so not exactly "shinny". But I did shoot some Federal, AE, and PMS that was nice clean brass. 

[washguy]

Its like what survival said...could be bolt bounce..cause its locking back....you need to somehow

try a dpms bcg rather than the jp to eliminate the jp bcg as a problem

:) Wash

[Powerman]

Its like what survival said...could be bolt bounce..cause its locking back....you need to somehow

try a dpms bcg rather than the jp to eliminate the jp bcg as a problem

:) Wash

 

But it seems from what limited info I read... that bolt bounce usually causes light strikes or no strikes. Or in full auto it causes other problems. How could bolt bounce cause ejection failures? I'm asking cause I have no clue.

[washguy]

But it seems from what limited info I read... that bolt bounce usually causes light strikes or no strikes. Or in full auto it causes other problems. How could bolt bounce cause ejection failures? I'm asking cause I have no clue.

 

Powerman   seems that the only thing left to swap out?  You did all the function tests right?  You held muzzle down and let bcg drop in to see if it binds or goes into almost full battery...gas tube is straight? right? charging handle  lets the gas tube go thru it right? chamber by now should be gtg..   locks back on one round/...right?  I still would go to basics and put the dpms buffer/spring in there though...I also one time a had a mismachined buffer tube,but the rifle wouldnt lock back...drove me crazy till i found that. We all know its a timing probelmo...just a thought

:)  Wash

[Powerman]

Powerman   seems that the only thing left to swap out?  You did all the function tests right?  Yes

You held muzzle down and let bcg drop in to see if it binds or goes into almost full battery... No actually, I'll do that

.gas tube is straight? right? charging handle  lets the gas tube go thru it right? Yep

chamber by now should be gtg..   locks back on one round/...right? Yep

I still would go to basics and put the dpms buffer/spring in there though...I also one time a had a mismachined buffer tube,but the rifle wouldnt lock back...drove me crazy till i found that. We all know its a timing probelmo...just a thought

:)  Wash

 

Cool. Thanks. I'll do that when I have some more time. I checked my brass and it's not frosted. It is driving my crazy. :)

[survivalshop]

But it seems from what limited info I read... that bolt bounce usually causes light strikes or no strikes. Or in full auto it causes other problems. How could bolt bounce cause ejection failures? I'm asking cause I have no clue.

Bolt bounce is where the BCG is moving too fast & compressing the spring in the receiver extension to max compression & bouncing off ,( weak spring , too light of buffer or wrong or mismatched components ,( receiver extension,buffer , buffer spring) ) The BCG is moving so fast that the spent case is past the ejection port before its released from the bolt & gets contained it the upper receiver & can cause other problems also , that you don't seem to have .

 

Your extractor may be holding  the spent case too long , its a timing thing , all functions must be done at a predetermined  time to function correctly & if one is slow or premature , it will screw things up.

 

Usually a rough or tight chamber will leave an exaggerated extractor mark on the spent case or may just sit in the chamber & not be ejected.

 

The mag catch can be too loose & not hold the mag securely , but not too tight ,to where you can not release the mag.. I set mine up on 308AR's to where I can't release the mag. & then one turn at a time out, till the mag can be released properly .

 

You have your mags numbered , when you shoot & the rifle fails , put that mag aside & test the next one & if all your mags fail to function the rifle , its probably not the mags.. I assume you are using different manufacturers mags .As said before , DPMS had a run of screwed up feed lips on some mags. & replace them under warranty .

[gsmopar]

Powerman   seems that the only thing left to swap out?  You did all the function tests right?  You held muzzle down and let bcg drop in to see if it binds or goes into almost full battery...gas tube is straight? right? charging handle  lets the gas tube go thru it right? chamber by now should be gtg..   locks back on one round/...right?  I still would go to basics and put the dpms buffer/spring in there though...I also one time a had a mismachined buffer tube,but the rifle wouldnt lock back...drove me crazy till i found that. We all know its a timing probelmo...just a thought

:)  Wash

 

 

Might be a coincidence, but are you using this one:  http://www.midwayusa.com/product/238414/dpms-buttstock-assembly-6-position-collapsible-lr-308-carbine-synthetic-black

[Powerman]

Bolt bounce is where the BCG is moving too fast & compressing the spring in the receiver extension to max compression & bouncing off ,( weak spring , too light of buffer or wrong or mismatched components ,( receiver extension,buffer , buffer spring) ) The BCG is moving so fast that the spent case is past the ejection port before its released from the bolt & gets contained it the upper receiver & can cause other problems also , that you don't seem to have .

 

Got it... most the stuff I was looking at was about the bolt bouncing back from the barrel extension.

 

Your extractor may be holding  the spent case too long , its a timing thing , all functions must be done at a predetermined  time to function correctly & if one is slow or premature , it will screw things up.

 

Ya, this last outing had the couple of stove pipes. That was new. All the times before it was just the casing and round jammed into the extension. 

 

Usually a rough or tight chamber will leave an exaggerated extractor mark on the spent case or may just sit in the chamber & not be ejected.

 

I checked my brass... it wasn't "frosted" like the video showed. there was a narrow band by the base that was "frosted" on the casings that jammed. My other brass is dinged up from being in the bag. 

 

The mag catch can be too loose & not hold the mag securely , but not too tight ,to where you can not release the mag.. I set mine up on 308AR's to where I can't release the mag. & then one turn at a time out, till the mag can be released properly .

 

If anything I have mine too loose. But I will check for sure where it is at, and then make sure it is set properly. 

 

You have your mags numbered , when you shoot & the rifle fails , put that mag aside & test the next one & if all your mags fail to function the rifle , its probably not the mags.. I assume you are using different manufacturers mags .As said before , DPMS had a run of screwed up feed lips on some mags. & replace them under warranty .

 

I had some CMMG steel mags before, but sold those. I could not tell you if they were good or bad. I now only have P-mags. And I have my original 5 I bought, and a box of ten that are new. So I have at least 2 different lots for sure. When I was having my malfunctions, it was 4 different mags for sure... possible 5. One of them new. 

 

 

 

So let's solve this buffer question... yes or no. I have the proper carbine extension tube, a AR10 H3 carbine buffer, and a Armalite AR10 spring that is uncut. I have a standard chrome Fulton armory carrier and JP bolt. Rifle length gas tube on a Fulton Armory barrel. Originally we were talking about gas leaks from the gas block... that I still have. I replaced the DPMS gas block with a PRI gas block. I thought about going adjustable, but did not see the need. 

 

I still have some leaks from the gas block... or at least the block/tube interface... but if anything my rifle seems like it is overgassed or properly gassed as opposed to under gassed. I have had the same issues shooting .308 or 7.62 NATO. If my rifle is indeed overgassed... BCG moving too fast... I could get an adjustable block and turn it down. 

 

If my BCG is moving too fast, then I at least DO have a correct buffer, right? And if anything I could possible get a heavier one from Slash. The Armalite H3 is 5.6 ounces, the CAR-10 is 5.7.... but he has buffers up to 6.8 ounces. So I could slow the bolt down by changing buffers as well correct?

 

I don't see the need to change one buffer for the same, but different maker. If BCG speed is in question then I get that. I also get we don't actually "know"... and yes I might have to slow it down and see. So what would be the best approach for that.... playing with buffers, or get an adjustable block and turn down the gas? 

 

My intention from this point is to stick with 7.62 as "plinking" ammo. That is what I will shoot mostly. My barrel is a 1:12.... so the heaviest I'll go is 175 gr... but most likely stick to 168 if I want to actually shoot something some day. 

Edited January 22, 2014 by Powerman

[Powerman]

Might be a coincidence, but are you using this one:  http://www.midwayusa.com/product/238414/dpms-buttstock-assembly-6-position-collapsible-lr-308-carbine-synthetic-black

 

No, I have a Magpul stock.

 

 

 

Here are the exact parts I have:

 

Tube

Buffer

Spring

Edited January 22, 2014 by Powerman

[Tripledeuce]

  My DPMS bbl had a "tight" chamber.   on a whim, I ran my finish reamer in, and removed metal the full length of the case body!   nothing on the shoulder, neck, or lead.   Just the case body.

    Would have played heck wit the case releasing from the chamber!

    Respectfully

    Terry

[Powerman]

So here is the brass that actually failed to eject. Not exactly "frosted", but there is a band at the bottom of the case....

 

 

I didn't notice before but on one of the stove pipes you can see a burr from the extractor.

 

 

And you can see my extractor is in good shape.

 

 

 

 

I just got off the phone with JP though. Learned a lot about extractors. Learned a bit about some of the common problems. Learned that they totally redesigned the extractor and spring and they should be getting them any day now. I certainly want one. They wanted some pics from me and we'll see what engineering has to say about it.

[washguy]

Hey Power here's a longshot thought...did you headspace your rifle?

prolly okay....but?

my feelings are your rifle has "Armaflu"...lol its down to the bcg...prolly jp bolt

and buffer tube ,spring ,buffer

I went back and read all the posts....is your rifle Armalite in respect to the receiver?

also....when you replaced the gas block....did you get the proper gas tube for the fulton rifle length barrel? 11/16 into lower is not enough protrusion

:) Wash

Edited January 22, 2014 by washguy

[Tripledeuce]

     I'd run a finish reamer in by hand.

    Respectfully

    Terry

[Powerman]

Hey Power here's a longshot thought...did you headspace your rifle?

prolly okay....but?

my feelings are your rifle has "Armaflu"...lol its down to the bcg...prolly jp bolt

and buffer tube ,spring ,buffer

I went back and read all the posts....is your rifle Armalite in respect to the receiver?

also....when you replaced the gas block....did you get the proper gas tube for the fulton rifle length barrel? 11/16 into lower is not enough protrusion

:) Wash

 

No, I did not head space my rifle. I know... 

 

I have a DPMS lower, and a Fulton Armory upper receiver. I'm pretty sure DPMS makes the upper for Fulton... or at least the same company makes for both, but I have never confirmed that. And the barrel and extension is FA. I ordered what I could from Fulton, but it was just the parts to complete the upper receiver and gas key for the carrier I got there.  

 

I bought my spare parts from Midway. Here is the gas tube:

http://www.midwayusa.com/product/395110/dpms-gas-tube-rifle-ar-15-lr-308

 

I have measured the 11/16" protrusion into the upper. Where the gas key joins the gas tube, there is a good 3/16". Where the tube is kept clean of fouling by the gas key going on. 

[Powerman]

     I'd run a finish reamer in by hand.

    Respectfully

    Terry

 

I have been reading plenty on polishing the chamber. I don't have a finish reamer. I do have a Smith close that probably could ensure the chamber is right. I could polish it or lap it. I did use the chamber brush in a drill, but would like to at least know my chamber is clean and clear. Seems reading on polishing/finishing a chamber is like which lube to use... quite a lot of differing opinions on what you should and should not do. Again, a finishing reamer would be fine... but I don't have one.

 

But looking at fulton, they do hand lap their chambers. If anything maybe I just need to ensure it is clean. But I did find that you can rent reamers on line.... and head space guages :) 

Edited January 23, 2014 by Powerman

[washguy]

Power   from another source:

+2 on the AR-10 tubes being 1/4" longer. I do believe that they are also the correct tube for the Fulton Armory barrels.

However, I also installed a standard AR-15 rifle tube on my 308. It does seem short, but I have experienced zero issues and it seems to make no functional difference.

Thats what I thought I remembered....Fulton takes the Armalite rifle length gas tube which is 1/4 inch longer

so,lemme ask you....if you have DPMS style upper/lower why did you put Armalite  buffer tube, buffer ,buffer spring in the butt?

and whats your answer to my question about the new gasblock you put in...you put a new gas tube on it or what?  :)  Wash

[Powerman]

 

Power   from another source:

+2 on the AR-10 tubes being 1/4" longer. I do believe that they are also the correct tube for the Fulton Armory barrels.

However, I also installed a standard AR-15 rifle tube on my 308. It does seem short, but I have experienced zero issues and it seems to make no functional difference.

Thats what I thought I remembered....Fulton takes the Armalite rifle length gas tube which is 1/4 inch longer

so,lemme ask you....if you have DPMS style upper/lower why did you put Armalite  buffer tube, buffer ,buffer spring in the butt?

and whats your answer to my question about the new gasblock you put in...you put a new gas tube on it or what?  :)  Wash

 

 

Really at the time it was price and availability. I was one of the stupid ones trying to build a rifle at the wrong time. :) I was confused over buffer/extension/springs... but then finally got it figured out. 

 

The DPMS buffer is light for their LR308, and most will later change to Heavy Buffers from Slash... but the Armalite H3 buffer is the same weight as Slash and less than half the price. I tried to spend money where I thought it was needed and save where I could... that was the buffer. The spring is just what works with the buffer. I could have used another one... and proper extension tubes were hard to come by. I do not have a actual performance reason... just price and availability at the time. 

 

I had the DPMS gas block... cheap. Then was told to swap it out which you read. I did not change the tube when I changed the block. The DPMS block was leaking a little at the block/barrel, but it was also leaking from the tube. The PRI replacement is also leaking from the tube. I still have fouling in front and rear. But other say they do too. I do not think it is leaking from block/barrel. I can swap out tubes, but most indications show I am properly/over gassed instead of under gassed which would be the case with leaks. But again, I don't actually know because I am new to the platform. So I really appreciate you helping me out. 

 

So then... other said about how far the tube is in the receiver... but how far does/should the tube go into the gas key... if my tube was 1/4" longer, it would be close to a half inch.

Edited January 23, 2014 by Powerman

[98Z5V]

     I'd run a finish reamer in by hand.

    Respectfully

    Terry

 

 

Yep, those circular scratches around the body of the brass - those aren't scratches.  That's a rough chamber.  That's the only way those could have happened, in the rifle.

 

I have a DPMS lower, and a Fulton Armory upper receiver. I'm pretty sure DPMS makes the upper for Fulton... or at least the same company makes for both, but I have never confirmed that. And the barrel and extension is FA. I ordered what I could from Fulton, but it was just the parts to complete the upper receiver and gas key for the carrier I got there.  

 

 

Upper manufacture doesn't matter, but DPMS does make those uppers, and lowers, for Fulton Armory.

 

What you need to be concerned about here is that JP made your bolt, and it's a Fulton barrel, and the two weren't headspaced.  That is, unless you sent that JP bolt to Fulton when you bought the barrel, and they headspaced it for you (they will do that when you buy any barrel from them).

 

You need to headspace check that combo...

[Powerman]

 

Yep, those circular scratches around the body of the brass - those aren't scratches.  That's a rough chamber.  That's the only way those could have happened, in the rifle.

 

Upper manufacture doesn't matter, but DPMS does make those uppers, and lowers, for Fulton Armory.

 

What you need to be concerned about here is that JP made your bolt, and it's a Fulton barrel, and the two weren't headspaced.  That is, unless you sent that JP bolt to Fulton when you bought the barrel, and they headspaced it for you (they will do that when you buy any barrel from them).

 

You need to headspace check that combo...

 

No, it has not been head spaced. I'll talk to a smith and see if he can ream it and headspace it for me. 

 

Unless anyone wants to lend me their gauges... I'll pay of course.

 

 

So I have been reading about polishing. So what is the best way to take care of a rough chamber? I have plenty of lapping compound... but it's silicone carbide and plenty say that is a no-no in firearms. I could do what many do and just use some Fitz and a chamber mop. there are the Flex Hones I could get from Brownells or Midway which seems the best bet. I don't want to do any "work", just make it right. I used the chamber brush... but that does not fix things.

[washguy]

Power if memory serves...lol...ive read your thread more than once start to finish...you asked about the placement of the gas block where it should be...right?... one time you said the gasblock was off the shoulder not a cards width but more...and no dimple am i correct? crap...remember ive got oldtimers...lol

then we all said nope should be just a cards width off...but I researched that for ya...fulton's gas port is further...so hence the longer tube.....but none of my 4 leak nada zero ..like your pics....placement does matter....when i build up one after the gasblock/tube is try mounted....I give it a BJ....stick my finger in the chamber...put mouth to muzzle and freakin blow....lol....you can hear the air coming out the gasblock into barrel.

so you are leaking at the barrel? right? and leaking at the gastube in the gasblock too? right?

im trying to condense all this....and then there's the jp bolt...and you dropped all that bcg stuff in the sand first time out? right? hmmmmm ...so you cleaned it all off by doing what? maybe sand and your bolt did a job on the lugs/chamber? crap.....im trying to help out an HK brother....so thats why all the questions...thinkin out loud.... Terry may have it...on the polish job (reamer)....

I run a plain ol dpms car 308 buffer dpms spring on a plain ol milspec tube on 3 of mine and a tubbs spring on another....and not a burp .......dpms did have some crap mags out there at onetime,,but you got pmags? you say it locks back/?right? redo the gasblock with proper gas tube....reamer like Terry said

:) Wash

[Powerman]

Power if memory serves...lol...ive read your thread more than once start to finish...you asked about the placement of the gas block where it should be...right?... one time you said the gasblock was off the shoulder not a cards width but more...and no dimple am i correct? crap...remember ive got oldtimers...lol

 

But the holes are not that big, and off a 1/4 would be covered. I have been thinking of taking the block off and actually measuring... I think I will do that to put it to rest and rule it out. That's easy. But yes, it's about a card off the shoulder.

 

then we all said nope should be just a cards width off...but I researched that for ya...fulton's gas port is further...so hence the longer tube.....but none of my 4 leak nada zero ..like your pics....placement does matter....when i build up one after the gasblock/tube is try mounted....I give it a BJ....stick my finger in the chamber...put mouth to muzzle and freakin blow....lol....you can hear the air coming out the gasblock into barrel.

so you are leaking at the barrel? right? and leaking at the gastube in the gasblock too? right?

 

I could actually see it leaking at the block/barrel with the DPMS. It always leaks on top though, not all the way around. So now with the PRI, it seems that the fouling on top is from the tube/block, not the barrel. The PRI is drilled all the way through... so the tube is visible at the front. The barrel itself from Fulton does not have dimples for the set screws for the block... but the block has never moved and the screws are lock-tighted. 

im trying to condense all this....and then there's the jp bolt...and you dropped all that bcg stuff in the sand first time out? right? hmmmmm ...so you cleaned it all off by doing what? maybe sand and your bolt did a job on the lugs/chamber? crap.....im trying to help out an HK brother....so thats why all the questions...thinkin out loud.... Terry may have it...on the polish job (reamer)....

 

I didn't drop the bolt, but it was really windy and there was sand blowing. A guy on the bench next to me cleared his off and splat. I'm a bit OCD so I was not happy... but it wasn't covered.  :)) But sure... absolutely possible the chamber could have been fouled or dirty with all I have done and running it really wet and getting oil all over. So at least I could understand how I had a good chamber, but don't now. At least on my bolt and carrier... it looks darn near brand new. Hardly any wear... certainly no wear that stands out as odd. Things look really good. I have even been watching and waiting for any wear patterns to develop... but none really at this point. 

I run a plain ol dpms car 308 buffer dpms spring on a plain ol milspec tube on 3 of mine and a tubbs spring on another....and not a burp .......dpms did have some crap mags out there at onetime,,but you got pmags? you say it locks back/?right? redo the gasblock with proper gas tube....reamer like Terry said

:) Wash

 

Back in the frenzy Fulton was not taking calls, but I could probably get in touch with them and find out for sure on gas tubes. I have Pmags and it is locking back on last round.

 

What is probably confusing you is that in the beginning I do know I was short cycling. I know I was not running enough lube on break in, and who knows what else with all the the other stuff block/mags/break in. My brass was landing right next to me and the bolt was not locking back. But that was back when it was new. 

 

It is not doing any of that now. The only problem I am having right now is failure to eject. Bolts locking back. Brass is landing very consistent before and after failures. 4 o'clock about 4-6 feet away... but it lands on concrete. So I absolutely need to figure out if it is a gas problem, but I do not have any other indications that it is. And I'm not ruling it out... I don't know. But I have given you all I know. I am game to try what ever. That's the point I am at. Square one and a fresh look. If you have a suspicion, I'm all ears.