Failure to feed for a rookie.

[washguy]

P-Man    If the rifle wasnt factory built you could have a wrong buffer spring and or a wrong buffer.....you gotta start off with the single round lock back first.....then you have gotta make sure you have the proper spring /buffer combo for your weapon....an ar15 spring /buffer  in a 308 will cause this   :))

[Powerman]

So I built my rifle. DPMS lower, FA upper/barrel/carrier, JP bolt. I have as AR-10 car buffer and spring and Car tube. I had some steel mags, but didn't use them. I use Pmags.

 

I can get through 5-6 or so mags before a problem. I throw somwe oil in, and it takes care of it for a while... then it is just sort of down hill from there. I asked about lube (sorry for multiple threads) and someone said it isn't a lube problem, so here I am.

 

5-6- or 7 mags the bolt locks back.. but that is only a few singles. I can do the singles and so on... but I can get through a 100 or so rounds before a problem. Take out the BCG, throw a bunch of lube all over it and the rings, and go back to shooting. Does not seem to matter between cheap NATO or exsprnsive SMK.

[shibiwan]

I have as AR-10 car buffer and spring and Car tube. 

 

I hope you got the correct combination of buffer/spring/tube. The AR10 carbine tube is 3/4" longer than the DPMS pattern tube for the 308AR (i.e. same length as an M4 car tube). The AR10 car buffer is also 3/4" longer than the DPMS pattern 308ar buffer.

[survivalshop]

Going that many rd's before a FTF , ummm?

 

Try a different manufactures magazine .

[shibiwan]

Going that many rd's before a FTF , ummm?

 

Try a different manufactures magazine .

 

 

...and sell me them 20LR pmags. LOL.

[Powerman]

I have 4 I use. I have a whole box unopened.

[washguy]

I hope you got the correct combination of buffer/spring/tube. The AR10 carbine tube is 3/4" longer than the DPMS pattern tube for the 308AR (i.e. same length as an M4 car tube). The AR10 car buffer is also 3/4" longer than the DPMS pattern 308ar buffer.

exactly!......P-man P-man get a chamber brush and solvent and scrub all that baked on lube/grease

out of your chamber! :) Wash cause this goes back to where you said you have been greasing up the bolt...and all that lube is burning in the chamber causing build up....and you say that she goes thru several mags till it starts happening....then you pour in more lube and its running...clean the frickin chamber and keep the grease off the bolt....the brass is sticking to the hot dirty chamber causing a timing cycling prolemo.....maybe so

Edited September 22, 2013 by washguy

[Powerman]

I use a chamber brush and mop. I know the chamber is clean after cleaning it. I only use a small dot of grease behind the lug on the bolt. I can understand if that is it, and I can certainly stop using it and see how it goes. That's an easy check. But I also don't see how something that is sort of common for some folks, can shut down a gun. If it is such a glaring problem, then you would think nobody would do it. I don't exactly take any one person's word as gospel, but the instructions in the video seem to come from a reputable source.

 

And this is no way a debate. I absolutley appriciate the input. I'm a rookie. Thanks for taking the time to share what you know. I will make sure it is clean. Coat of oil on the bolt, work the rings, and no grease on the bolt and see how it goes.

 

And for everything else... next session, I will be doing this much more methodicaly, take notes, check brass regularly, and begin to start pin pointing failures.

Edited September 22, 2013 by Powerman

[blue109]

I use the old chamber brush in a hand drill. My 5.56 AR wouldn't cycle wolf until I did it.

[Powerman]

I use the old chamber brush in a hand drill. My 5.56 AR wouldn't cycle wolf until I did it.

 Actually, I didn't think about that. Thanks.

[blue109]

I use a usgi section of cleaning rod. Its tough and won't bend, and the rough texture allows the drill to grip it tight.

[washguy]

OK, so I'm not the thread police... I don't mind them going where they go. But is there some sort of check list... things to look for to start pointing to a direction?

 

I know you guys know plenty and it isn't as simple as just saying A, B, an C. I troubleshoot plenty in my line of work... it "depends".

 

Obviously I could go over my build and we could try to get to the bottom of my problem... but where do you start? If you have a feed problem... or probably a better term would be a "jamming" problem... where do you start to untangle the tangle?

 

P man    your checklist is right here in this thread!  why dont you print out this thread and use it for a checklist....you started asking questions and were not clear on what was going on at first....there is no ar308 for dummies book....getting an ar 308 to run isnt rocket science either....if you cant figure it out after all the good suggestions in this forum then I suggest you take it to a gunsmith...although he prolly wont know crap about an ar308 either :))   Wash

[Powerman]

I hope you got the correct combination of buffer/spring/tube. The AR10 carbine tube is 3/4" longer than the DPMS pattern tube for the 308AR (i.e. same length as an M4 car tube). The AR10 car buffer is also 3/4" longer than the DPMS pattern 308ar buffer.

 

I know at the time I was on here and got all the advice needed to get the proper set up. I was a little confused at the time and got it figured out after asking. I just can't remember it right now, I would have to look it up. Super busy these days. But I know I got the short heavy AR-10 buffer and AR-10 spring. I did buy the wrong tube, and had to buy the proper one when I got it figured out. But that was all before I shot the first round.

[washguy]

"I had a DPMS one and there was gas leaking out. Fouling from under the block on both side. And yes, it was because I was trying to figure out jamming. But I also know that I did not use near enough lube when it was new. So I got a PRI because it was so highly recommended, and it does the same thing."

P-man...this is your quote on your other thread....people have been trying to help you and NOW you tell us this? your gas block is still leaking??? and you want a detailed start to finish booklet so you can go from A toZ to figure out what is wrong? Put the ar 308 down and slowly back away......then go get a nice bolt action rifle :) you wanna be spoon fed but you dont give us the correct info till after the fact :) Wash

[Powerman]

"I had a DPMS one and there was gas leaking out. Fouling from under the block on both side. And yes, it was because I was trying to figure out jamming. But I also know that I did not use near enough lube when it was new. So I got a PRI because it was so highly recommended, and it does the same thing."

P-man...this is your quote on your other thread....people have been trying to help you and NOW you tell us this? your gas block is still leaking??? and you want a detailed start to finish booklet so you can go from A toZ to figure out what is wrong? Put the ar 308 down and slowly back away......then go get a nice bolt action rifle :) you wanna be spoon fed but you dont give us the correct info till after the fact :) Wash

 

Seriously?  I asked for a some sort of direction to go about figuring out feeding problems. I'm not asking to be spoon fed anything. I figured a troubleshooting discussion might help me and others with these sort of problems. I wasn't asking to solve my particular problem. I was asking how other go about pin pointing problems.

 

Then I asked for proper lubrication for a 308 in another thread because that is an area where there is a bit of disagreement. I wasn't asking for spoons there either. I was asking for proper guide lines for amounts of lubrication.

 

I most certainly appriciate any input and experience/knowledge given that I can learn more from. But you can save you codesending B.S. about a bolt action.

[Matt.Cross]

Lay off the high octane java brews for a while fellas, no point in messing up the good atmosphere that is usually enjoyed here. Everybody take a deep breath and remind yourself that you're amongst friends.  <thumbsup>

[survivalshop]

Here is a list for you to start & others can add if they want.

 

As said , make sure you have the correct components , buffer ,spring , receiver extension (buffer tube )

 

Start out with the std. action drill , one round (does the BCG  travel far enough for the now empty magazine to hold back the Bolt Carrier Group)

two rounds , does the BCG hold back, three & so forth ,  till you get to the twentieth round in the mag.,you get the idea . You can install fully loaded mags & fire till you get a malfunction & take note on when & what type.

  You can use the same mag. & if you use the same brand of mag's , number them . I don't care what manufacturer's mag you use , any could cause a problem , they are mass produced.

 

Does the rifle malfunction at any time in the drill , stop & note the type of malfunction .

 

Inspect the fire control group (trigger,hammer , disconnector )all working to spec's ? Any unusual wear  on any component ?

 

Make sure the gas block is correctly installed , even if you have to take it to some one to make sure.

 

This is only a partial list & there is much more . Don't let this get the best of you , you have to be some what of a detective on some rifles to get them to fully function to spec's , The answer is there & probably some thing simple .

 

As far as a little grease , I've been repairing & building ,both select fire & semi auto AR's for over thirty years & never had a problem with using it. The key is , as with any thing else , is do not over do it . 

 

 

 

 

[gsmopar]

As far as the buffer tube; what are the lengths of each?  It was stated earlier that the 308 is 3/4 in longer, but what is the total length so those of use newbies with FTE problems can go measure their guns.  Thanks!!!!!   :auto:

[Powerman]

Mine is all AR-10 with a 7 5/8" Vltor tube.

 

Next time at the range, I will just shoot 3 or 5 round groups and chack brass as I go. I want to find out when the bolt starts scraping them.

 

What is the story on ejection... where should your brass be? What does it tell you where it is ejected?

[98Z5V]

Powerman, I checked out this thread late on the first day that you'd posted it.  I saw some of the answers given to you, so I didn't reply.  No need, especially since survivalshop gave you the most common answer to your general question - mags are the primary cause.  Others listed other causes, and it was pretty well covered. 

 

I saw the thread go into two pages, then three, so I checked into the thread to see what was up.  I was kinda shocked to see, at the top of page 3, Matt's response.  At that point, I went through the whole thread to try to find out where things went sideways, and caused that reply by Matt.  I found it.

 

 

I don't necessarily want to diagnose a specific problem, but have a discussion on the topic.

 

Well, that ^^^ was the first thing I saw on the subject when I first opened it, and I saw about a 1/2 dozen replies giving you info. 

 

So this is cool... lot's of different things. And I want to know other things... but obviously, I have a specific FTF problem I am trying to figure out.

 

I think everything is fine until it does not feed. If I look at my brass, you can see scrape marks. I'm assuming it is the bolt lugs. When it gets bad, the the brass is gouged and jammed by the bolt not going all the way back and picking up the round at the end.

 

This round was a little different. The brass was caught up top and inside the receiver, and the mouth was jammed up against a barrel lug I guess and was sort of split open.

 

So can brass help diagnos certain problems?

 

This is definitely "conflicting information," here in red.  You said nothing in specific, but it was something specific - you kinda screwed yourself. 

 

Those scrape marks on your brass aren't from the bolt lugs.  They're from the barrel extension.  Not a big deal, in the least, unless you're concerned that they've cut the brass, and it might be weak to reload.  Function-wise, those scrapes don't matter.

 

 

I knew you were going to say that... I didn't keep them. I know, stupid. At leas the different ones. I have plenty of the gouged up ones.

 

If you are looking at the barrel from the breech... then when a jam did occure, the spent brass was at like 10:00, with the new round trying to get in the chamber. The spent brass was inside the reciver to the inside of the new round. The spent case was jammed into the barrel lugs which dented the mouth of the case in. (I assume) But this was new... never saw this before. And I thought it odd that the brass was inside... meanig was this more failure to eject which caused the FTF?

 

Any other time though... brass is thrown a good 4 feet to 4-5 o'clock position. All land in the same place.

 

 

Above ^^^, that's a double feed, or a failure to eject.  You got the round out of the chamber (extractor is working), but the round didn't eject from the rifle (ejector problem).  There's a topic on possible ejector problems going on right now, elsewhere on the board.  It's got the details.

 

As far as all the "ejection pattern" stuff - overgassed, undergassed, wrong weighted buffer - I personally don't care where it goes, as long as it goes in the same general direction, and as long as it gets out of my rifle.  I'm not going to chase "ejection modification" solutions over somebody saying "it should always land in a pile at 3:30 about 4.78 feet away..."   As long as it routinely clears my rifle, I don't think it matters where it goes.  My $0.02. 

 

So I built my rifle. DPMS lower, FA upper/barrel/carrier, JP bolt. I have as AR-10 car buffer and spring and Car tube. I had some steel mags, but didn't use them. I use Pmags.

 

I can get through 5-6 or so mags before a problem. I throw somwe oil in, and it takes care of it for a while... then it is just sort of down hill from there. I asked about lube (sorry for multiple threads) and someone said it isn't a lube problem, so here I am.

 

5-6- or 7 mags the bolt locks back.. but that is only a few singles. I can do the singles and so on... but I can get through a 100 or so rounds before a problem. Take out the BCG, throw a bunch of lube all over it and the rings, and go back to shooting. Does not seem to matter between cheap NATO or exsprnsive SMK.

 

I guess you stated it later in the thread, but in this specific post here ^^^, you mentioned your buffer parts, but not the manufacturer.  If those parts aren't all from Armalite, or Armalite branded (specifically, that receiver extension), then you might have issues with the combination.

 

As far as the buffer tube; what are the lengths of each?  It was stated earlier that the 308 is 3/4 in longer, but what is the total length so those of use newbies with FTE problems can go measure their guns.  Thanks!!!!!   :auto:

 

AR-15 carbine receiver extensions have an internal depth of 7".  Doesn't matter how long they are on the outside, because the outside doesn't affect the function of the weapon.  You should always measure the internal depth, when trying to determine a problem.  The Armalite AR-10 CAR receiver extension

 

 

Mine is all AR-10 with a 7 5/8" Vltor tube.

 

Next time at the range, I will just shoot 3 or 5 round groups and chack brass as I go. I want to find out when the bolt starts scraping them.

 

What is the story on ejection... where should your brass be? What does it tell you where it is ejected?

 

This very well be the problem.  That VLTOR receiver extension is for the VLTOR A5 buffer system, designed for a 20" AR-15, in order to increase the reliability when running it with a collapsible stock setup.  That's the only thing it's designed for.  The Marine Corps runs this combination frequently.

 

This is everything I want to reply to.  I'll get to it later, and modify this post.    Updated, with comments.  I'd like to see Slash from HeavyBuffers jump in here with input.

Edited October 1, 2013 by 98Z5V

[survivalshop]

This is everything I want to reply to.  I'll get to it later, and modify this post.

 

<munch>

[Powerman]

Was there going to be a follow up?

[98Z5V]

Yeah, I need to compose it.  I'll work on it today.

[98Z5V]

Updated, with responses above.  Don't take it personal.  It's tough enough to diagnose problems when you've got a rifle sitting right in front of you, and you're taking it apart - let alone on the internet.  These are just my views from going into the whole thread after seeing everything thus far. 

[Powerman]

Well, that ^^^ was the first thing I saw on the subject when I first opened it, and I saw about a 1/2 dozen replies giving you info. 

 

 

This is definitely "conflicting information," here in red.  You said nothing in specific, but it was something specific - you kinda screwed yourself. 

 

But I wasn't asking to fix my problem. I was asking on advice on how others begin to diagnose problems. Yes I have a problem of my own which is why I am interested in the subject to begin with, but I was not asking to fix my specific problem.

 

I have already asked about my specific problem before in other threads about my build. And sometimes, when problems are trying to be diagnosed, especially in situations like these on the web... things get skipped over or taken down a path that might not be right. Or people just say A, B, C... without the why or the how... "the not being taught to fish thing if that makes sense".  I was trying to go back to square one, and start from the beginning. I do not think that was being unreasonable. That when these things happen, where do you start, and how do you start ruling things out? And I certainly got just that from a few people. And good suggestions that I will try next time I'm at the range.

 

Now if I am asking the impossible and nobody can give what I'm asking, then it's all good. I'll have to start with the suggestions given, start a specific thread, and then go from there.

 

But then I was accused of trying to solve a specific problem and not giving all the info... which is not what I was doing. As far as the suggestion of stepping back and walking away and getting a bolt gun... well, I think you already know what I think about that.

 

Those scrape marks on your brass aren't from the bolt lugs.  They're from the barrel extension.  Not a big deal, in the least, unless you're concerned that they've cut the brass, and it might be weak to reload.  Function-wise, those scrapes don't matter.

 

That makes sense. Before I thought it was related... when a case would jam and be gouged and dented by the bolt... but the scratches I can understand.

 

 

 

 

Above ^^^, that's a double feed, or a failure to eject.  You got the round out of the chamber (extractor is working), but the round didn't eject from the rifle (ejector problem).  There's a topic on possible ejector problems going on right now, elsewhere on the board.  It's got the details. I'll look at it.

 

As far as all the "ejection pattern" stuff - overgassed, undergassed, wrong weighted buffer - I personally don't care where it goes, as long as it goes in the same general direction, and as long as it gets out of my rifle.  I'm not going to chase "ejection modification" solutions over somebody saying "it should always land in a pile at 3:30 about 4.78 feet away..."   As long as it routinely clears my rifle, I don't think it matters where it goes.  My $0.02.  Cool.

 

 

I guess you stated it later in the thread, but in this specific post here ^^^, you mentioned your buffer parts, but not the manufacturer.  If those parts aren't all from Armalite, or Armalite branded (specifically, that receiver extension), then you might have issues with the combination.

 

 

AR-15 carbine receiver extensions have an internal depth of 7".  Doesn't matter how long they are on the outside, because the outside doesn't affect the function of the weapon.  You should always measure the internal depth, when trying to determine a problem.  The Armalite AR-10 CAR receiver extension

 

 

 

This very well be the problem.  That VLTOR receiver extension is for the VLTOR A5 buffer system, designed for a 20" AR-15, in order to increase the reliability when running it with a collapsible stock setup.  That's the only thing it's designed for.  The Marine Corps runs this combination frequently.

 

This is everything I want to reply to.  I'll get to it later, and modify this post.    Updated, with comments.  I'd like to see Slash from HeavyBuffers jump in here with input.

 

I'll have to look up my specific parts I ordered... but at the time I found out my tube was wrong, I posted up my parts and links and got the blessing from you guys here. Not saying that could not be an issue, but that was what I went through when I was putting my build together. I measured the tube when I got it and it was 7 5/8" like I needed.

 

Tube

Buffer

Spring

 

I certainly appreciate all the help from everyone. But I'm not a dumb arse, and don't appreciate being talked to like one. Smiley face or not. I'm just new to the AR platform and am trying to learn more. If I seem like a ungrateful douche... well then that's on me. My bad.

Edited October 1, 2013 by Powerman