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omnip0tent

308 Build... Carbine buffer w/ Rifle gas??

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Hello all,

 

Im building my first .308. Its going to be mostly an Aero build. I've got most of the parts selected. I've already built my lower, and need to decide on my upper (going to buy a built one hopefully from AERO)

 

My big question is....

I want a collapsible stock, so will the carbine buffer system i've purchased work with Rifle gas system? Or should i go mid length to be safe?

I've heard mixed reviews on if it will be under gassed or not.

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Your stock choice has no bearing on the length you choose for your gas port. At all. Is this your first AR build? Maybe we can help you with your choice if you tell us a little more about you and your expectations for this weapon.

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13 minutes ago, edgecrusher said:

Your stock choice has no bearing on the length you choose for your gas port. At all. Is this your first AR build? Maybe we can help you with your choice if you tell us a little more about you and your expectations for this weapon.

I 've pieced together my ar-15 lower, and bought a complete BCM upper ( that was my first rifle)  It was great and easy.

This will be my 2nd rifle, and I wanted a .308... (It's all DPMS)

*** I've purchased:

-Aero m5 stripped Lower

- Aero m5 LPK (w/o FCG & Grip)

- Trigger and Grip of choice (magpul and CMC)

- Aero m5 Carbine buffer extension with buffer, spring, backplate & castle nut

- My Carbine stock of choice (magpul Sl-S i think?)

*** I need to purchase the ENTIRE UPPER.

My plan was to buy an entire Aero Upper with Aero BCG. But I've noticed most of them come with a Rifle gas system. I was told that a rifle gas system on an 18" barrel, with a carbine buffer/spring might cause problems with the rifle fully cycling. They mentioned a Mid-Length gas system would guarantee cycling but might make for harsher recoil.

 

As I have 0 experience with .308 AR's I just want input.

 

I WANT an 18"-20" barrel, but with a collapsible stock. So again I think the question stands:

Will a rifle length gas system on an 18"-20" barrel, work just fine using a carbine buffer/spring/extension?

 

 

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Ya got 2 different things going on brother 1 has nothing to do with the other.

I have an M5 setup 16" mid-gas upper has Nickel boron BCG and an Aero receiver, spring, and buffer.

I had some FTE/FTF issues and went to a complete Armalite set up. That seems to be the fix. I have  RRA 20" rifle gas with a carbine setup without issue.

.308AR's unless it's a pistol is either mid-gas or rifle.

 

 

Edited by unforgiven

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3 minutes ago, unforgiven said:

Ya got 2 different things going on brother 1 has nothing to do with the other.

I have an M5 setup upper had Nickel boron BCG and an Aero receiver, spring, and buffer.

I had some FTE issues and went to a complete Armalite set up. That seems to be the fix.

 

 

Sorry if my post sounds ignorant. Just came here to learn. So what exactly do you mean I have 2 different things going on?

1) My entire build consists of AERO m5 stuff (Minus the furniture) so this is all DPMS pattern if I am not mistaken. I will not be switching to armalite because I already have the DPMS Aero Lower. And from all the reading I've done, now I will need a (DPMS) pattern upper.

 

2) My question specifically is referring to the barrel length and gas system I choose, working with the carbine buffer I have.

Here are some links so you guys can see my concern specifically. WILL THESE TWO PARTS WORK WELL TOGETHER IN A BUILD?

-https://aeroprecisionusa.com/m5-308-carbine-buffer-kit.html

Work with

-https://aeroprecisionusa.com/m5e1-308-18in-rifle-ss-complete-upper.html

 

Or would these 2 parts be cause for concern of the gun being undergassed?

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No worries bro I learn something new here all the time.

So let's see if I don't fuk this up : 3 different gas designations

closest to you on the barrelthe gas port would be consided carbine gas..it is said to have a slightly sharper recoil [ in 5.56 ] would you notice...only you know. 

The the gas port closest to the muzzle would be rifle gas [ with a slightly] recoil pulse.

Of course the port between the 2 is mid gas. If you looked at the specs you get a dimension as to location. So as the projectile leaves the barrel the puff of gas goes down the gas tube to move the BCG to strip and chamber the round. So have the proper weighted buffer and spring with the correct length receiver tube allow the BCG to go back and forth in perfect time. Any hitch/drag and timing will be off.

Make any sense ?.

 

 

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5 minutes ago, unforgiven said:

No worries bro I learn something new here all the time.

So let's see if I don't fuk this up : 3 different gas designations

closest to you on the barrelthe gas port would be consided carbine gas..it is said to have a slightly sharper recoil [ in 5.56 ] would you notice...only you know. 

The the gas port closest to the muzzle would be rifle gas [ with a slightly] recoil pulse.

Of course the port between the 2 is mid gas. If you looked at the specs you get a dimension as to location. So as the projectile leaves the barrel the puff of gas goes down the gas tube to move the BCG to strip and chamber the round. So have the proper weighted buffer and spring with the correct length receiver tube allow the BCG to go back and forth in perfect time. Any hitch/drag and timing will be off.

Make any sense ?.

 

 

Yep I follow all that. But without actually having all these configurations to test myself I am asking you guys who hopefully have shot a few different configs for input.

 

Will an 18"-20" barrel with a rifle gas system, function with a Carbine buffer/spring/extension. Or do you think there might be some issues with this config?

-https://aeroprecisionusa.com/m5-308-carbine-buffer-kit.html

-https://aeroprecisionusa.com/m5e1-308-18in-rifle-ss-complete-upper.html

 

 

Im thinking the confusion might be that my question is so obviously dumb you're not even registering my concern. & of course that barrel length w/ rifle gas system will work with any carbine buffer stuff.

 

Edited by omnip0tent

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No my man. There should be no issues.  What my friend here was trying to tell you is that many people go to the Armalite buffer system because it’s a proven system that will work (some carbine parts do work well, others do not). But normally buffer system has nothing to do with your receiver sets or bolt carrier group /barrel, where is mixing and matching generally is a no go (and here is where you can use the Armalite buffer parts with any brand receivers) If you continue to use the parts that you have listed you should have no problem. Again if you do we will help you.

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Thanks for the info guys.

 

Just to clarify: You CAN use an Armalite buffer system with any pattern .308 AR rifle, DPMS or Armalite?

Do you guys happen to have a link of the Armalite buffer system just so I can indulge my curiosity?

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Hey guys I don't mean to 2nd guess all of your input but I've had a buddy re-word my question as I think you guys don't fully understand what I'm asking...

I'm asking "if there are issues running an M4-style receiver extension with rifle gas on an 18" rifle?" Which I've been told there will be short stroking issues.

Edited by omnip0tent

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Okay.

As long as you're running a carbine-length BUFFER and SPRING in a carbine receiver extension, you should be good to go. If you run a heavy-weight buffer or spring, you may have short stroking problems. If you run a rifle-length buffer in a carbine extension, you will have problems. If you run a rifle-length spring in a carbine extension, you may have problems. Make sure all your buffer parts are appropriate for your extension, and you should be fine.

Tuning an AR platform rifle is a balance between gas and buffer. Too little gas or too much buffer/spring results in short stroking. It really is that simple.

With a .308, 18" barrel and rifle gas, you should be good to go with a carbine receiver extension, carbine buffer, and carbine spring.

If it short strokes, find a lighter buffer or spring.

Building an AR is equal parts science and art -- what works for one person, on one particular build, may not necessarily work for the next person building the same thing.

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27 minutes ago, omnip0tent said:

I'm asking "if there are issues running an M4-style receiver extension with rifle gas on an 18" rifle?" Which I've been told there will be short stroking issues.

I run a 16 inch rifle gas barrel with a carbine extension. No issues but I had to open the gas port up on my X-Caliber barrel, it was way undersized from the factory. Criterion sells 16 and 18 inch rifle gas barrels, I built around the 18 inch and had no issues. As long as the gas port is proper size you will not have an issue. If the gas port is undersized you will have an issue with whatever size extension you use.

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Ok. The answer is still the same, no matter how many times you ask, worded differently with the same meaning. Use the search option. This topic has been beaten to death at least 5 times over in several long threads.

 

You’ve read something somewhere else or have been given poor information by someone who doesn’t have the knowledge base on this platform needed to properly assist you. There is a huge knowledge base here. On more than AR platform too. 

 

See if if this helps you understand better, Mr Raley was the head armorer for Armalite for an awful long time up until 5 years ago I believe.

 

 

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I think i see where this gentlemen is getting confused.  I believe the info he's been told/ read on other forums is about the AR15 and not a 308AR.  reason i say this is because i built a AR15 rifle gas 18".  The questions he's asking is the troubles ran into with this setup on Ar15 platform. 

What they are trying to explain to you is, Yes the rifle gas setup should work in your build.  But, there is no guarantee because the 308AR's can be finicky to get tuned right.  them pointing you to the Armalite carbine buffer kit, is because it'll work on any 308AR no matter if it's DPMS style or Armalite.  it's just a 100% proven setup to work right the first.

I'm in the process of building my first 308AR too.  It's pretty much the same parts list as you're using. ( Just mine will be in 243, instead of 308) But, I bought the Armalite Carbine kit on the recommendation of the forum members here.  Once you read throught the forum here, you'll see these guys will steer you in the right direction with as few headaches as possible. 

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On 3/13/2018 at 1:29 PM, omnip0tent said:
On 3/13/2018 at 1:29 PM, omnip0tent said:

Hey guys I don't mean to 2nd guess all of your input but I've had a buddy re-word my question as I think you guys don't fully understand what I'm asking...

I'm asking "if there are issues running an M4-style receiver extension with rifle gas on an 18" rifle?" Which I've been told there will be short stroking issues.

Fuk it, I got this.

Okay, I made this two quotes, because I'm making two statements here.

First, your buddy rewording your question - what's his background?

Second, you want to know if there are issues running an M4-style receiver extension with rifle gas on an 18" rifle.  NO, there are not.  I presume that you're asking that specific question, that your buddy reworded for you, and you're referencing a 308AR platform.  Is that correct?  I'm not trying to be a dik, I'm just trying to make sure there's no confusion, and be clear.

So, pictured below is a 5.56 rifle with rifle length gas and an 18" barrel, and an "M4-style receiver extension.  This thing runs like a champ, and nothing can stop it.  So, based on that, as evidence that a rifle with an 18" barrel and rifle length gas and an M4-style receiver extension, not only works, but works great...  you need to know this part - a 308 .Win round is making ALOT more gas than a puny 5.56 round, and a 308AR will have NO TROUBLE running a setup just like that.

Here's the 5.56 gun.  The one on top. It's proven, and it's badass.  :thumbup:

Mk12s.jpg

 

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And here to heap a bit more confusion on this, YES it will run given the correct buffer spring/buffer is used with the 308AR.  I have an APF manufactured (DPMS style) 16" barrel (rifle length gas system) that worked flawlessly utilizing a carbine buffer system, but changed to a rifle length ONLY because I prefer a fixed stock. The main difference was mine was put together by the manufacturer, and they had done their homework. It just ran, and ran.....when fed correct spec ammunition.

As far as the info previously given, it is spot on, just confusing when you are a newbie....no crap intended to the OP.

I made mine run intermittently with just a change in the buffer weight, when trying to diagnose function problems that were not fully understood,  nor firearm related, and chased my tail for a bit.....quite needlessly.

 

Edited by bubbas4570
tighten up description, hoping for clarity

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