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Louiswp

What did I do wrong? Help

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I built up an LR308, I fired it a few times and it seemed fine, didn't blow up. But it did leave little "C" Mark's on the casing rim, seemed to toss the casing about 1 or 2 o'clock, and cycled without jamming and BCG stayed locked back when empty. Kicked pretty good and loud.

Figured I would work on tuning later. My suppressor approval came so I fired one shot with the suppressor, casing ejected at roughly 3 o'clock but not 100% sure. Jammed and pinched the next bullet pretty good. Dented the casing.

Both times I used Hornady 168 match bthp, didnt want to use my reloads testing a new rifle.

This is what I have, something must be wrong.

18" CMMG barrel,

gas tube length 15",

gas block non adjustable. .936? Dia 

15" handguard 

Bcg aero precision and upper

Buffer tube 7-1/4 long

Buffer spring 10-7/8 long, 25 coils. .070

Buffer weight 2-1/2" long. No idea oz.

 

 

 

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Your buffer is too light.  Especially suppressed, when you induce MORE gas pressure on a gas system that might be doing it's job- but your recoil system isn't up to the task to begin with.

Bare minimum - your 2.500" buffer should not be running in a receiver extension that 7 1/4" long - that's TWO bad parts combined together, right there.  MEASURE THE INTERNAL DEPTH OF YOUR RECEIVER EXTENSION.  It either needs to be 7.000" internal, or it's 7 5/8" internal.  THAT is the number that matters here.

You need a buffer that weighs 5.4oz, or very damn close.  Your 2.500" buffer will weigh 3.8oz, when you weigh it. Not Enough Ass To Control The Mass...

Fix your Recoil System FIRST.  Make a functional gun, no suppressor, FIRST.  After that, we'll talk about what it takes to make it run suppressed.  Functional guns need a good recoil system - and you don't have that.  Suppressed guns need an adaptable gas system.

Two different animals.

Edited by 98Z5V

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Thank you for the info, I have some leg work to do and will follow the process you posted. I will get back when I change the buffer system out and fire it again. Suppressor was bought for my TRG so I thought I would fire a round and see what happens. I will get it tuned before trying to suppress it. 

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1 hour ago, Louiswp said:

Thank you for the info, I have some leg work to do and will follow the process you posted. I will get back when I change the buffer system out and fire it again. Suppressor was bought for my TRG so I thought I would fire a round and see what happens. I will get it tuned before trying to suppress it. 

What suppressor did you end up going with? 

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13 hours ago, 98Z5V said:

Your buffer is too light.  Especially suppressed, when you induce MORE gas pressure on a gas system that might be doing it's job- but your recoil system isn't up to the task to begin with.

Bare minimum - your 2.500" buffer should not be running in a receiver extension that 7 1/4" long - that's TWO bad parts combined together, right there.  MEASURE THE INTERNAL DEPTH OF YOUR RECEIVER EXTENSION.  It either needs to be 7.000" internal, or it's 7 5/8" internal.  THAT is the number that matters here.

You need a buffer that weighs 5.4oz, or very damn close.  Your 2.500" buffer will weigh 3.8oz, when you weigh it. Not Enough Ass To Control The Mass...

Fix your Recoil System FIRST.  Make a functional gun, no suppressor, FIRST.  After that, we'll talk about what it takes to make it run suppressed.  Functional guns need a good recoil system - and you don't have that.  Suppressed guns need an adaptable gas system.

Two different animals.

Any recommendations on a quality buffer assembly that meets those specs? Looks like everyone is sold out

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6 hours ago, Louiswp said:

Any recommendations on a quality buffer assembly that meets those specs? Looks like everyone is sold out

This will suit your needs well.  Even though it is Armalite brand, it will do what you need.  It appears to be in stock at the moment.  If it is not, call them on the phone.  They will frequently make a kit if you ask.

https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories/Lower-Receiver-Parts&Category=ac614400-ff09-4cdf-9d35-419a654e7201

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On 9/8/2020 at 11:29 PM, 98Z5V said:

Your buffer is too light.  Especially suppressed, when you induce MORE gas pressure on a gas system that might be doing it's job- but your recoil system isn't up to the task to begin with.

Bare minimum - your 2.500" buffer should not be running in a receiver extension that 7 1/4" long - that's TWO bad parts combined together, right there.  MEASURE THE INTERNAL DEPTH OF YOUR RECEIVER EXTENSION.  It either needs to be 7.000" internal, or it's 7 5/8" internal.  THAT is the number that matters here.

You need a buffer that weighs 5.4oz, or very damn close.  Your 2.500" buffer will weigh 3.8oz, when you weigh it. Not Enough Ass To Control The Mass...

Fix your Recoil System FIRST.  Make a functional gun, no suppressor, FIRST.  After that, we'll talk about what it takes to make it run suppressed.  Functional guns need a good recoil system - and you don't have that.  Suppressed guns need an adaptable gas system.

Two different animals.

My tube is 7" inside. Are you saying I can just up my weight or do I need everything swapped. The gun shop knows less than me. He said what I have should work fine. But it doesn't. He has lots of parts but not friendly. He has a luth-ar rifle length I will try for now.

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On 9/8/2020 at 11:36 PM, 98Z5V said:

Read this, for providing pertinent gun details:

Read this, for understanding gas systems and recoil systems:

 

After that, go rip up the Intro Section, and tell us about yourself.  It's right here:

https://forum.308ar.com/forum/22-introductions/

My gas tube at least appears correct. Looks like the one in the example.

20200911_151152.jpg

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I bought a rifle length tube and buffer assembly 5.3 oz. From a local shop. Online was sold out.

Finally fired it without the silencer.

Looks like it ejects around 1 or 2 o'clock. Definitely forward.

Casing has a dimple and skid mark where the carrier ejector hits then turns under pressure.

See pics.

Pics with two casings is with the carbine length and 3.4oz buffer? You can see it was ruining the brass and putting "C" Mark's.

Single casing is the just fired. Much better, and reusable for my TRG-22 reloads.

 

20200915_120629.jpg

20200915_120418.jpg

Edited by Louiswp
Grammar

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Post a pic of your ejector face - it's got a squared-off face, on the top of it.  It's running too fast, as well.  Too much gas - or more often than not, NOT ENOUGH recoil system...   Standard Hornady .308 Win loads shouldn't be suspected as "hot loads."  So, it's not the ammo.  It's the gun. 

2002794538_badejector.jpg.3ee3a58b179c13a3b053d0130d9f0735.jpg

Squared off ejectors cause rounds to jam, when they're coming out of the right side of the double-stack magazine.  Squared off ejectors also fuk brass up, and leave some nasty ejector smears on brass, when something is out-of-whack with the gun, and it's running too fast.  More often than not, it's a too-light recoil system that's making the gun cycle too fast.  Close runner up to that prize is a gas system that's way over-gassed.  It's not usually the gas system, though.  It's a manufacturer that's saving money making cheaper recoil-system parts, and the buffer is too light, and the spring is actually an AR15 spring...  Cheaper that way, to make and sell them.

Regardless - rounded off ejectors don't usually leave ejector smears, like you're showing in that pic above. We're only looking at one step of the issue here. 

Edited by 98Z5V

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20 minutes ago, 98Z5V said:

Post a pic of your ejector face - it's got a squared-off face, on the top of it.  It's running too fast, as well.  Too much gas - or more often than not, NOT ENOUGH recoil system...   Standard Hornady .308 Win loads shouldn't be suspected as "hot loads."  So, it's not the ammo.  It's the gun. 

2002794538_badejector.jpg.3ee3a58b179c13a3b053d0130d9f0735.jpg

Squared off ejectors cause rounds to jam, when they're coming out of the right side of the double-stack magazine.  Squared off ejectors also fuk brass up, and leave some nasty ejector smears on brass, when something is out-of-whack with the gun, and it's running too fast.  More often than not, it's a too-light recoil system that's making the gun cycle too fast.  Close runner up to that prize is a gas system that's way over-gassed.  It's not usually the gas system, though.  It's a manufacturer that's saving money making cheaper recoil-system parts, and the buffer is too light, and the spring is actually an AR15 spring...  Cheaper that way, to make and sell them.

Regardless - rounded off ejectors don't usually leave ejector smears, like you're showing in that pic above. We're only looking at one step of the issue here. 

Currently has 13 fires on it. Aero Precision brand. Buffer is 5.4? Go higher still?

20200915_230757.jpg

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6 minutes ago, Louiswp said:

Currently has 13 fires on it. Aero Precision brand. Buffer is 5.4? Go higher still?

20200915_230757.jpg

This tube is rifle length 9 3/4 inside, 5.4 oz buffer that's 5 1/4" long, spring is 12 7/8 with 38 coils.only in stock option I could get.

 

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8 minutes ago, Louiswp said:

Currently has 13 fires on it. Aero Precision brand. Buffer is 5.4? Go higher still?

20200915_230757.jpg

Well, you don't have a squared off ejector face, that's just been determined. 

Let's take a look at something else here.

On 9/8/2020 at 9:13 PM, Louiswp said:

18" CMMG barrel

^^^  What's the gas port diameter on that barrel?  And, are you sure it's 0.936" diameter for the gas block?

This all comes down to a question from before, when asking for gun details - and we MEAN DETAILS...  This must have been glossed over, with this suggestion:

On 9/8/2020 at 9:36 PM, 98Z5V said:

Read this, for providing pertinent gun details:

 

 

After that, go rip up the Intro Section, and tell us about yourself.  It's right here:

https://forum.308ar.com/forum/22-introductions/

By the way - you never did heed the suggestion to post an Intro about yourself - so go get into that in your spare time.  Your "free information" is over, until you accomplish that task.

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What was the solution?  Care to share so we all can learn a little?  Glad it’s working and hope the suppressor works out well when that time comes. 

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4 hours ago, DNP said:

What was the solution?  Care to share so we all can learn a little?  Glad it’s working and hope the suppressor works out well when that time comes. 

I am going to run about 50 rounds through it. Then get back to what I did. I made my own adjustable buffer to adjust to whatever oz. I want. And a few other mods. Finally said hell with it and used my aerospace experience to make my own parts.

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6 hours ago, Louiswp said:

Looks like the whining comment was deleted. Quite a forum. At least most put in the effort to be cordial.

Are you contextualizing the whole forum by one deleted comment, or did I misunderstand your meaning?

This is a great community of folks and we do our best to welcome newcomers. I'm not sure what your beef is here....

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7 hours ago, Louiswp said:

 At least most put in the effort to be cordial.

You're welcome.

Thanks for playing.  Feel free to stick around, and provide the information asked of you initially.  Or not.

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