Problems with AR10 build, cycling and bolt catch on empty mag

[Mikejames]

I recently just built my first AR and decided to go with mostly Aero Precsion parts. Everything is Aero except for the pmag, Faxon non-adjustable gas block, Faxon 18” rifle length barrel. I’ve had trouble with it from day one. At first it wasn’t cycling the next round, and it got worse with higher-grain round I went. Just this past week it has started to cycle better but I went ahead and put a adjustable gas block on thinking it was just over-gassed. I ended up blowing the gas block out because I adjusted it to far open. Once I put the old gas block on from Faxon it cycled fine. I still haven’t had it lock on an empty mag however. I’ve had 3 different gunsmiths look at it and they all have said different things (over-gassed, magazine, buffer system). I was curious as to if anyone has had these problems or knows a fix to it. The buffer system is the aero kit with a 3.8 ounce buffer. I’ve used 147, 165, and 175 grain rounds. 

[98Z5V]

19 minutes ago, Mikejames said:

The buffer system is the aero kit with a 3.8 ounce buffer.

This might be the issue.  Measure the internal depth of the receiver extension (tape measure will work, down the extension until it bottoms).  Get that info back here, in this thread.  That buffer is 2.500" long, and that receiver extension needs to be on the money at 7.000" internal depth. Not a little over, not a little under.

That buffer weight is shiit.  The spring probable sucks.  Also, how many rounds downrange so far? Gas systems need to seal, and it takes a little carbon fouling to get that done. 

Hit the intro section.

[Mikejames]

I’ll get the length tomorrow, I don’t have the gun with me right now. But I’ve ran about 60 rounds through it so far. 

[jtallen83]

6 hours ago, Mikejames said:

I ended up blowing the gas block out because I adjusted it to far open.

Pictures? Could you elaborate on this? Never heard of such a thing, I would think it was defective to start with if it failed.

A note for future clarity, you have a 308 AR not an AR 10. AR 10 is an Armalite platform and a somewhat different animal when it comes to many parts.

[unforgiven]

The solution for many here me included was the Armalite system receiver extension,buffer, and spring. Done. Just my 2 mags

[survivalshop]

Measure the Buffer Spring length & count the Coils on it , Measure the Depth of the Receiver Extension , as has been said  , nothing wrong with the DPMS Buffer system if correct components used. Why spend more $$ if not needed . 

Once this info is posted here , it may have clues as to what is going on . I too want to hear about the blown out GB . 

[Mikejames]

Sorry for the late response, but the internal length is 7" and the coils are 24 between the two end coils. I had it checked for me earlier since I am not home an able to mess with the gun. Now regarding the gas block. I had it put on by a gunsmith in town, and once it was on i headed back to the house to adjust it. It had 20 clicks of adjustment in it. I ran about 16 rounds through it trying to get the bolt to lock on an empty mag. Opening it up more and more with every round. I  must have just adjusted it open to much where the screw was loose or something because when i shot a FTE happened and smoke was everywhere at the front of the gun. When i looked the adjustment screw was gone and the front was open and i could see the detent spring. The gas block was a Odin Works. Sorry for making it sound catastrophic, wasn't exactly an exploding gas block.

Edited December 2, 2018 by Mikejames

[Mikejames]

There is the lower showing the spring and the rifle to see if anyone notices something strange or abnormal. 

Photos.app.zip

[survivalshop]

Nice Rifle . How long is the Buffer Spring , the Coil count is low . Should be around 11.5 "  & around 29 coils , counting the two ends still make it short , if that is the way you counted .Buffer length should be 2.5" . The 7" depth is correct for a DPMS type Carbine Receiver Extension . DPMS system uses AR 15/M16/M4 Receiver Extensions for the LR 308 Ar's , both Rifle & Carbine types . Armalite AR 10's us their own proprietary Receiver Extension & Buffer Springs for their AR 10 &  use AR 15/M16/M4 Buffers , usually a Heavy Buffer type Buffer.

The two different systems components can not mixed .

[98Z5V]

The problem with these 3.8oz buffers (Aero doesn't make a bad one - it has two tungsten weights in their aluminum body), comes down to the springs.  Carbine recoil systems will run on a .308AR (DPMS LR-308s prove that).  All these manufacturers think that they're gonna make the next, greatest thing, and make everything in-house.  They don't get the spring right.  Buffer weight is 3.8oz, which is as heavy as they can make it without spending money on a stainless buffer body, and just using tungsten weights.

The biggest issue that you'll see is what everyone calls "over-gassed."  "My AR-10 is over-gassed!  I need an adjustable gas block!!!..."  

First, you have to inform them that it's not an AR-10.  AR-10s don't use that type of recoil system construction.  AR-10 Carbine recoil systems work every time...

The next battle with them is informing them that they do not "need" an adjustable gas block, because they are not "over-gassed."  They are actually "under-recoiled."  The recoil system is weak, and not up to the task of handling the .308 Winchester rounds (and just about anything else we can shoot in this frame type).

The recoil system was designed to be run with a 5.4oz buffer as it's primary operating weight, inside a receiver extension that's 7 5/8" long.  Any change to either of those dimensions requires a complete change in the three system components.  Most common change is the receiver extension, and the use of the AR15 Carbine receiver extension with it's 7.000" internal depth.  Next "victim of specs" is the buffer weight - it goes down.  It has too, because it needs to be shortened to 2.500" long to work in a 7.000" extension.  What's the final thing that manufacturers can't get right?  The operating spring.  Most .308AR OEM Carbine operating springs are junk.  

Once you understand the difference in what you have and what you need for a recoil system, it becomes more clear on what's really going on with your rifle - it's not over-gassed.  It's under-recoiled.  Adding the adjustable gas block puts the bandaid on the wrong cut...

Edited December 2, 2018 by 98Z5V

[survivalshop]

3 hours ago, 98Z5V said:

The problem with these 3.8oz buffers (Aero doesn't make a bad one - it has two tungsten weights in their aluminum body), comes down to the springs.  Carbine recoil systems will run on a .308AR (DPMS LR-308s prove that).  All these manufacturers think that they're gonna make the next, greatest thing, and make everything in-house.  They don't get the spring right.  Buffer weight is 3.8oz, which is as heavy as they can make it without spending money on a stainless buffer body, and just using tungsten weights.

The biggest issue that you'll see is what everyone calls "over-gassed."  "My AR-10 is over-gassed!  I need an adjustable gas block!!!..."  

First, you have to inform them that it's not an AR-10.  AR-10s don't use that type of recoil system construction.  AR-10 Carbine recoil systems work every time...

The next battle with them is informing them that they do not "need" an adjustable gas block, because they are not "over-gassed."  They are actually "under-recoiled."  The recoil system is weak, and not up to the task of handling the .308 Winchester rounds (and just about anything else we can shoot in this frame type).

The recoil system was designed to be run with a 5.4oz buffer as it's primary operating weight, inside a receiver extension that's 7 5/8" long.  Any change to either of those dimensions requires a complete change in the three system components.  Most common change is the receiver extension, and the use of the AR15 Carbine receiver extension with it's 7.000" internal depth.  Next "victim of specs" is the buffer weight - it goes down.  It has too, because it needs to be shortened to 2.500" long to work in a 7.000" extension.  What's the final thing that manufacturers can't get right?  The operating spring.  Most .308AR OEM Carbine operating springs are junk.  

Once you understand the difference in what you have and what you need for a recoil system, it becomes more clear on what's really going on with your rifle - it's not over-gassed.  It's under-recoiled.  Adding the adjustable gas block puts the bandaid on the wrong cut...

I disagree , the Armalite Ar 10 Buffer system was designed its way & the DPMS Buffer was designed its way , they do both work , just two ways of accomplishing it . If you mean OEM Springs from DPMS are junk , you are saying that the tens of thousands that are out there working with out issue are junk , that's just an opinion , not a fact , because the facts don't prove other wise . Every time we get into Buffer System issues , you & other Armalite pushers , say thats the only way to build a Buffer system & the only one that will work , thats not a fact , only opinion . It may have been the first way of accomplishing it in a 308AR type Rifle , but when using the correct components , the DPMS Buffer system works just fine , the proof is in how many are actually working ( many many more then AR 10's I might add ), you can't blame a system by what manufacturers or suppliers submit sub par components or parts or builders using miss matched parts ( which is partly suppliers fault for not labeling them incorrectly )

Order a real DPMS Buffer Spring from DPMS or one of their authorized suppliers or Dealers & it will work .?

[98Z5V]

5 hours ago, survivalshop said:

I disagree , the Armalite Ar 10 Buffer system was designed its way & the DPMS Buffer was designed its way?

You can disagree with Eugene Stoner all you want - he designed it, and he designed it before DMPS bastardized an AR15 part to make a 308 with a collapsible stock on it.  If you have information otherwise, please post that first DPMS LR.308 with a collapsible stock, that came before the AR-10 Carbine.  I'll be waiting...

Disagree as much as you want - that's the ground truth, right there, and it was designed to operate on a 5.4oz buffer.  Period. 

DPMS made a bandaid, in order to put AR15 parts on the 308, and they did their homework, and the straight-from-them big carbine recoil system works.

That doesn't mean that everyone gets it right, now does it?  Hardly any of them CAN get it right...  Tell me I'm wrong... 

Please read CAREFULLY what I stated, SS:

Carbine recoil systems will run on a .308AR (DPMS LR-308s prove that).

 

Now, in that confession, straight from me, did I acknowledge that DPMS gets it right?  You're damn right I did.  However, you have to go throw this out there, because you didn't read what I stated...

If you mean OEM Springs from DPMS are junk , you are saying that the tens of thousands that are out there working with out issue are junk , that's just an opinion , not a fact , because the facts don't prove other wise .



"If you mean..."   I did NOT mean that, and if you read what I posted, you would know that.

So, here's what I'd like to see - you find me ONE DPMS-BASED Carbine Recoil System that doesn't have problems, that is NOT using DPMS Genuine Parts.  Just to be clear, and ultra-clear to you, DPMS LR-308 Carbine springs do work, but only with a 3.8oz buffer.  OTHER OEM springs from OTHER OEM MANUFACTURERS USUALLY SUCK, AND DO NOT WORK.  Happy? 

[98Z5V]

5 hours ago, survivalshop said:

Every time we get into Buffer System issues , you & other Armalite pushers , say thats the only way to build a Buffer system & the only one that will work , thats not a fact , only opinion .

That's what you READ when we say it - and you're interpreting it wrong.  That's on YOU, buddy, no one else.

When people ask, I will tell them that I can guarantee that I can list parts that WILL work, if they get the parts I say - and I give them part numbers to search for - and guess what?  They WORK!  Every single time!     You want a carbine recoil system for your Big AR that won't let you down?  Buy Armalite AR-10 parts.  They work, every time.  Find these part numbers...  I even state OTHER receiver extensions that will work, and I tell people to get ANY AR15 H3 buffer? 

You go run out here and try to tell people that they need DPMS parts to get their recoil system running - and most of them are going to tell you that they HAVE DPMS parts already.  YOU take up that argument with them, and explain the difference in DPMS factory parts, and the amount of JUNK that's out there on the market.  Shiit, almost everything a vendor lists is "AR-10" in the listing, and it's DPMS-Based...   You fight that fight  - it's not worth it.  Meanwhile, I'll recommend parts that work, by part number, and include variances that work, too - just like I always have here...

So, how is that an Armalite pusher?!...   Are you nuts?  I don't even own an Armalite AR-10 , man, so quit climbing up on that horse, so you can fall off it again.  I'm not an Armalite pusher.  I push parts that WORK...   I hope you understand that. 

[98Z5V]

@survivalshop, here is my most recent recommandation, just so you know:

If you have no recoil system parts yet, just get the whole Armalite AR-10 Carbine recoil system. 

You can do the whole kit (one part number), or piece it together.  There are three companies that I know of that are doing a confirmed 7 5/8" internal depth receiver extension, so there are options if some things are outta stock.  Armalite AR-10 Carbine, VLTOR A5 (couple of different ones), and MagPul SR-25/M110.  Any one of those three, Armalite EA1095 spring, any AR15 H3 carbine buffer (or the Armalite AR-10 Carbine buffer, same/same).

That came from this thread:

 

[jtallen83]

I am an Armalite fan, no doubt. My last 308AR had no Armalite parts but nothing close to the DPMS recoil system either, Vltor receiver extension, Tubbs spring, and a PWS H3 buffer. I much prefer the options I have available when using the longer extension, adding tungsten weights instead of buying a whole new heavy buffer.

When asked to list parts for friends and family builds I list the AR-10 system, not because I am a fan but because it simplifies the process, I know it will work for them and I don’t have to spend time researching some part they found on sale. Nothing against DPMS.

[survivalshop]

21 hours ago, 98Z5V said:

You can disagree with Eugene Stoner all you want - he designed it, and he designed it before DMPS bastardized an AR15 part to make a 308 with a collapsible stock on it.  If you have information otherwise, please post that first DPMS LR.308 with a collapsible stock, that came before the AR-10 Carbine.  I'll be waiting...

Disagree as much as you want - that's the ground truth, right there, and it was designed to operate on a 5.4oz buffer.  Period. 

DPMS made a bandaid, in order to put AR15 parts on the 308, and they did their homework, and the straight-from-them big carbine recoil system works.

That doesn't mean that everyone gets it right, now does it?  Hardly any of them CAN get it right...  Tell me I'm wrong... 

Please read CAREFULLY what I stated, SS:

 

 

Now, in that confession, straight from me, did I acknowledge that DPMS gets it right?  You're damn right I did.  However, you have to go throw this out there, because you didn't read what I stated...

 

 

"If you mean..."   I did NOT mean that, and if you read what I posted, you would know that.

So, here's what I'd like to see - you find me ONE DPMS-BASED Carbine Recoil System that doesn't have problems, that is NOT using DPMS Genuine Parts.  Just to be clear, and ultra-clear to you, DPMS LR-308 Carbine springs do work, but only with a 3.8oz buffer.  OTHER OEM springs from OTHER OEM MANUFACTURERS USUALLY SUCK, AND DO NOT WORK.  Happy? 

 I think you need to re read your post , you stated OEM , that means original Equipment Manufacturer, you're talking about DPMS , because they are the OEM for a DPMS components .

 Eugene Stoner only designed the Armalite AR 10 & that's the way he designed it , not the DPMS LR 308 , DPMS designed it , two different Rifles , its said here all the time , so you can argue thats the way he designed the AR 10  & your correct , I never said he didn't , as far as bastardizing the LR 308 with AR 15 components , I suppose Mr Stoner didn't by using the M16 Buffer in the AR 10  , be it his design or not, its the same logic . I see nothing wrong with using off the shelf parts & components for weapon systems .as long as the function correctly !

My disagreement was with you & others come on as the AR 10 based Buffer system is the only way to have a Buffer system , reread your post . No argument with you about sub par non OEM Buffer Components , but your exact wording was Most OEM, go back & read it . What that reads is most DPMS Carbine Buffer Springs are junk , thats not the case & there are a lot of the after market Buffer Springs that are not to spec & those are the ones we see have issues here . 

The reason I even posted was that you made it sound as the AR 10 Based system is the only one that works on a 308AR & Its not the first time its been said , you can say all you want about under Recoiled , thats just opinion , show me facts & I will believe it , I don't push one system or the other , I do try to save someone some $$ by fixing a DPMS based System they already have , with miss matched or incorrect parts , not selling them a complete Armalite system , you need to go back & re read all my posts about the subject & show me where I said its the only way to go , Like this from you & you didn't specify AR 10 , it was a general comment  " The recoil system was designed to be run with a 5.4oz buffer as it's primary operating weight, inside a receiver extension that's 7 5/8" long."  Yes the AR 10 was designed that way , but the DPMS was NOT & I'll say it again , their are tens of thousands of DPMS Carbines running with DPMS designed components , so prove other wise that they are under recoiled . Just think of all the DPMS Based Carbine 308AR out there that don't come on a Forum with an issue because of miss matched or out of spec Parts thats something you can not argue with or show they dont work., I can say this the AR 10 system is only a fraction of what is out there based on the DPMS system & I don't say that that thats a bad system , just different .?

Edited December 4, 2018 by survivalshop

[edgecrusher]

Let’s just say that if you go with the correct DPMS or Armalite systems you will be all set. The unfortunate thing is many parts companies and some manufacturers don’t know the difference 

[Armed Eye Doc]

29 minutes ago, edgecrusher said:

Let’s just say that if you go with the correct DPMS or Armalite systems you will be all set. The unfortunate thing is many parts companies and some manufacturers don’t know the difference 

Or think they can improve on one or the other.

[98Z5V]

You go, SS.  You stick with that.   

 

[survivalshop]

I will ?

Edge is right , must be QC be it at the sub contractor or the end seller isn't . Makes it bad for builders who believe that they are getting the correct parts .

[98Z5V]

15 hours ago, survivalshop said:

?

Makes it bad for builders who believe that they are getting the correct parts .

Easy way to cure that, too - use Armalite AR-10 Carbine recoil system parts...  

[survivalshop]

 

9 hours ago, 98Z5V said:

Easy way to cure that, too - use Armalite AR-10 Carbine recoil system parts...  

or if you have a DPMS based system ,get the Proper Spring,Buffer & Receiver Extension , be it an actual DPMS one or a reputable copies. After all a correct 308LR Carbine Buffer Spring is only $ 8-9 .?

   Ya thats a good idea , have large frame AR  Builders waiting for parts for years , because Armalite can't even keep up with what's out there now ? Which just happens to be a very small segment of the market for large frame AR Receivers & Rifles , oh & just wait till they mass produce them , I'm sure everyone will be perfect .

    .I believe they only Patent that Armalite holds is the type of Receivers & Bolt , there are others that make the same length Receiver Extension & they can't say they have a patent on Spring length , certainly not Heavy M16/M4/AR15 Buffers , too many make them now .

 

[jtallen83]

Armalite has pretty much completed their move so parts availability is not an issue like it was.