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FTF / NO LOCK BACK last round


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Having fail to feed and fail to lock open after last round.  

Local shop built gun.

First testing it wouldnt cycle but few times till jam. Took back to shop.

Got it back and cycled 110gn Fine but not 168gn or 150gn would jam. Bolt catch would realease at lightest bump of gun. Took back shop. Said it be few weeks before could try come up with solution and i juss left with it.    

So it had an ar15 bolt catch. I figured that out and put correct one in. 

Dpms?  Lr308.  

Local shop branded lower. (Think was 80% they finished)

20in barrel. (Unknown brand shop doesnt remember) Rifle length gas system .077 gas port 

Buffer tube 7in internally.  Buffer 3.8oz. Spring 9.5in 25coil

Adjustable gas block. Slr7 maxed out 15 clicks. Tried all settings

Forward assist is on backside of deflector and doesnt match where serrations are on bolt carrier. Can see silver plunger at bottom left of bolt


Also every casing is being shrunk in 2 spots towards neck can see rings in pic. Close to 100 all look this way doesnt matter gn. Or brand


From my measurements my gas tube is almost 1/2in  in gas key on bolt and could go 1in?


JAM once every few rounds. 


Casing 1 ring 1/4in from were bullet would be and another ring 1/4in from were gets bigger


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So they porked ya bud. Truth. But we are here to help. Start reading, check out pinned topics and hit up the intro thread. And don’t ever go back there again. How do you not know what parts you’re using in a build for a customer? 


First things first. Your buffer and spring as as wrong as Biden and Kamala. Junk both and keep the tube for small AR parts and buy a complete Armalite system. Or keep the tube and get a KAK buffer and springco orange spring. 

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Go get the gun back from the gunshop - or leave it with them and ask them for your money back.  Either way, is the best thing that you can do.  They don't know what they're doing.

We'll build you a gun, or fix the one that you have (depending on that barrel).  The marks on those rounds you posted are from slamming into the feedramps. 

If it was mine, I'd tell them that it's fucked beyond all repair, and I want my money back - they can sell that thing to someone else.

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Not near enough recoil system. KAK buffer and springco orange spring or complete Armalite carbine recoil system. Buffer should weigh in the 5.5oz range. Either one of the above should get things running. Your bolt is running to fast and the magazine hasn't raised the next round enough to feed correctly. That's why it's smashing the rounds into the feed ramps.

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On 9/8/2021 at 12:26 AM, DJ619 said:

Im stuck with it. They had it for the first 2 months i owned it and thats when decided i got better luck fix it myself. 

Start with my suggestions on your recoil system. That may help the slamming into the feed ramps, it’ll definitely help your cycling and feeding/extraction issues. 

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1 hour ago, shooterrex said:

The other thing I see wrong is your gas tube is a little short. Probably an AR-15 gas tube. Pick up an Armalite rifle length gas tube it is a bit longer. That will also slow the bolt just a bit.

Gas tube is damn near there, right in the middle of the cam-pin cutout in that upper receiver, from the pic he posted.  I'd leave the gas tube alone for now, and focus on that recoil system.  Fix that, and we move to gas port diameter int he barrel, next.  Gas tube doesn't look bad to me.

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1 hour ago, DJ619 said:

This the only kit i can find with same deminsions as whats on it. 

Luth ar 308 buffer kit. Screenshot_20210907-103455_Chrome.thumb.jpg.140cfcbf34587aafd5ccd044bd59ece1.jpg


No, hell no, Full Stop. 

You need THIS.  Period.

Armalite part number AR10REKIT01.  Everything else that stated that "it's the same" is just cobbled together shiit, and it is NOT the same.


It's out of stock right now - but look up their contact information from the link I just gave you, and call them on the phone, talk to a human. You might be surprised.

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3 hours ago, edgecrusher said:

So they porked ya bud.

This was Epic.  :thumbup: 

I have further comments about this reply, but I'll hold them for later.  It's not against the OP, but that simple sentence explains everything that PSA does with their PA-10 platforms. 

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GO TO ARMALITE.COM  Contact number 623-780-1050.  CALL THEM.  I had an AR shop change the but stock on my DPMS LR-308.  Then found this site.  I checked the spring and buffer.  They were AR-15.  It will NOT work with the bigger cals.  I checked Armalite web site and the extension kits were out of stock.  I called and told them my problem.  The man I talked to said that he would dig around and put a kit together for me.  I think it shipped the next day.  THAT IS customer service.  I didn't even go back to the shop that did the work.  They went out of business a few weeks later.  I am still learning to pay attention to the people here.  I bought a RRA trigger before getting info. here.  Will most likely return the trigger and buy a Larue 2 stage.  JMHO   🥺🥺🥺


Edited by Steve crawford
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On 9/8/2021 at 6:02 PM, DJ619 said:

Called armalite today. Was told place a backorder online and it should be sent out within 4weeks...  

I can have tungsten buffer weights  in few days. Would changing my weights in buffer require different spring? How long is a 308 carbine buffer tube supposed be?

We need exact measurements of your buffer and spring or you can get the KAK buffer and orange Springco spring

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2 hours ago, edgecrusher said:

We need exact measurements of your buffer and spring or you can get the KAK buffer and orange Springco spring


Spring length 9.5"     25coils


Outer length 7" 3/16


Buffer weight 3.810 oz



Inner length 6" 15/16 (is flush with lower reciver at top of threaded part)


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