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

[98Z5V]

8 hours ago, Billd said:

Yes it will work just fine but you'll need use the 3.7 oz buffer 

I have a lr 308 with 20in barrel  clasp able ar 15 but stock with 3.7oz buffer  and have shot over 1000 round with no trouble what is ever 

That's a SMALL gas port in that barrel, if it's running right.  Stick around, and review some information.  Tell the guy to run a 3.7oz buffer isn't normal - that's usually what fucks these guns up.  Oh, and they're 3.8oz buffers, for H1 buffer weight. 

Bad advice, on your part.

[GLB]

On 3/13/2018 at 11:51 AM, omnip0tent said:

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?

An 18 in barrel with a rifle length gas tube should be used with a rifle buffer system. It’s that simple. If you need confirmation on an Aero M5 308 build just contact Aero Precision. You can get the carbine buffer system to work just as long as you stay within narrow parameters.  But, given the experience I had with this build I could easily pick a number of 308 ammo types found on any shelf an introduce short stroking issues with that carbine buffer system  .  If you absolutely have to have the adjustable carbine style stock, then run 308 PMC Bronze.  That gave me no problems with using a carbine buffer system with a rifle length gas system.  But, branch out from there and good luck especially if you want to run premium match 175 or 185 grain ammo.  Once I took the advice from Aero and replaced the carbine buffer system with rifle buffer system, I was able to run anything through my Aero Precision M5 308 build not just select 147-150 grain ammo.

 

 

[98Z5V]

12 minutes ago, GLB said:

An 18 in barrel with a rifle length gas tube should be used with a rifle buffer system. It’s that simple. If you need confirmation on an Aero M5 308 build just contact Aero Precision. You can get the carbine buffer system to work just as long as you stay within narrow parameters.  But, given the experience I had with this build I could easily pick a number of 308 ammo types found on any shelf an introduce short stroking issues with that carbine buffer system  .  If you absolutely have to have the adjustable carbine style stock, then run 308 PMC Bronze.  That gave me no problems with using a carbine buffer system with a rifle length gas system.  But, branch out from there and good luck especially if you want to run premium match 175 or 185 grain ammo.  Once I took the advice from Aero and replaced the carbine buffer system with rifle buffer system, I was able to run anything through my Aero Precision M5 308 build not just select 147-150 grain ammo.

I think this is what you stated - can't tell because the quote was messed up.  What I've highlighted in bold red above is NOT accurate information - if that came from you.  Just letting you know that.

I can give you a million reasons why your information is NOT accurate. 

Edited December 9, 2021 by 98Z5V

[Reichenbach1976]

On 3/13/2018 at 3:16 PM, omnip0tent said:

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?

I just built and aero M5 Lower with Aero Carbine M5 buffer kit (collapsible stock)  on a 20” Aero upper and immediately its a 1 shot rifle.  Short strokes every time.  I don’t know best way to fix and keep carbine collapsible stock.  If I can’t I need to know if ai should sell stock and buffer and convert to a full length rifle stock and buffer tube.

[shooterrex]

Your recoil set up has to handle the mass of the BCG coming back and reloading the rifle. IT DOESN'T MATTER rifle,carbine, mid length as long as everything balances out.

I use Armalite carbine recoil set up on 20" rifle and a 12.5" pistol and a 16"  rifle.

Look up the Waterboarding thread and answer those questions and we have a better chance of helping you get this gun running with more data.

[Armed Eye Doc]

The first question is  how much does your buffer weigh?

[edgecrusher]

On 2/27/2022 at 3:45 PM, Reichenbach1976 said:

I just built and aero M5 Lower with Aero Carbine M5 buffer kit (collapsible stock)  on a 20” Aero upper and immediately its a 1 shot rifle.  Short strokes every time.  I don’t know best way to fix and keep carbine collapsible stock.  If I can’t I need to know if ai should sell stock and buffer and convert to a full length rifle stock and buffer tube.

To solve your issues we need some measurements. The M5 buffer kit has been found to be incorrect. The buffer should weigh 5.4 ounces. From the we need a measurement on the internal depth of the tube, length of the buffer, and length of the spring. Lastly details on your barrel, more specifically the gas port diameter and journal. These measurements will help us diagnose your issues and get your rifle running with any ammo.

[blue109]

If your gas port is sized correctly on the barrel, you will have the same gas pressure reaching the carrier regardless of barrel configuration, so it has no bearing on the recoil system you use. My 16" rifle gas system has a significantly larger gas port than a 16" carbine gas system. The goal is optimum operational pressure running down that gas tube. This isn't always the case as it's not an exact science. If you are overgassed, you can run an adjustable gas block or heavier buffer/spring to compensate. If you are undergassed you can open it up. Buying quality parts that are known to work together can mitigate your troubleshooting but there are no guarantees with big frame ARs. Keep in mind... adjustable gas blocks can only REDUCE gas. I constantly see people acting like it's a bandaid for every problem. 

 

Several of us are running carbine stocks on rifle length guns. Some of us are running carbine stocks on 16" rifle length gas guns. It's common and totally doable. The armalite recoil system is unquestionably better but the DPMS system works fine in most cases. It's just a different approach to the same problem. The carrier is long. DPMS decided to use a standard tube and a stubby buffer. Armalite decided to use a longer tube and a standard buffer. There are spring and buffer weight options for both systems. 

[Reichenbach1976]

Sorry guys I just saw these posts.  I tried taking of m5 carbine buffer and used vltor re-a5 tube 7 5/8” deep with armalite ea1095 spring and h2 buffer 3.25” long but it was still a single shot to maybe two shots then failure to load next round.  Gas port hole is 0.096 I believe.  At top end of spectrum.  Everything is aero except the 20” barrel, gas tube,  gas block, and bolt came from a cbc industries .308 kit I ordered.  Its very accurate but not reliable.  
 

i got aggravated and sold off the M5 carbine buffer kit, and vltor/armalite parts.  Im getting ready to buy the aero m5 rifle buffer kit like Aero told me to do.  This has been a terrible investment.

[Armed Eye Doc]

2 minutes ago, Reichenbach1976 said:

h2 buffer 3.25” long

You needed the H3 buffer.  It is 5.4 ounces and the H2 is 4.6 ounces (IIRC).  The rifle system will work as well.

[98Z5V]

41 minutes ago, Reichenbach1976 said:

Its very accurate but not reliable.  

I've stated for a very long time here that the barrel and trigger are the heart of your accuracy.  The gas system and recoil system are the heart of your reliability.  I have that information in a very, very long thread that I've made, describing all these parts, and how they interact - and either work together or not.

42 minutes ago, Reichenbach1976 said:

i got aggravated and sold off the M5 carbine buffer kit, and vltor/armalite parts.

Research and the correct parts selection - as well as questions here before selling all those great parts off - would have prevented this.  We could have fixed this gun, easily, and made it run like a champ.

42 minutes ago, Reichenbach1976 said:

This has been a terrible investment.

No, it's not.  It's just incorrect parts selection, that didn't work together, and the gun didn't work.  Because of the incorrect parts used.  Again, we could have prevented this, had the details been given beforehand.  That didn't happen, though. 

You never balanced the recoil system to the gas system - and the gun didn't run. 

Read this - it's been here since 2018, when I got tired of seeing information such as yours, and made this thread, specifically to address mis-information on this weapons platform:

 

[98Z5V]

WHOOOO!!!     You're gonna be busy - I just saw your other thread, and gave out information in that one.  You need to balance both threads now, with the info that will be poring in...   Should have kept everything in one thread.  

[huck]

Hi, All. I'm new here. 

omnipotent, if you're still about, how did this project Of yours from 2018 end up?  Have an assembled Aero M5 lower with carbine buffer system and am thinking of getting  a fully assembled Aero upper with a full length gas system and  an 18 in barrel. Next best option is a mid-length gas system and a 16 in barrel.

let me know, thanks. 

[shooterrex]

2 hours ago, huck said:

Hi, All. I'm new here. 

omnipotent, if you're still about, how did this project Of yours from 2018 end up?  Have an assembled Aero M5 lower with carbine buffer system and am thinking of getting  a fully assembled Aero upper with a full length gas system and  an 18 in barrel. Next best option is a mid-length gas system and a 16 in barrel.

let me know, thanks. 

 

Who's carbine buffer system?

What does the buffer weigh?

What is the internal depth of the buffer tube?

What spring are you using?

Your barrel length and gas system length doesn't really matter if you have the proper gas port diameter for the length barrel balanced by the recoil system with the proper weight buffer and spring.

The buffer should weigh close to 5.5 oz .