AR Buffer discoveries

[H&R Glock]

Since I got the new 7.62x39 upper from the Bear Den (Bear Creek) I got worried about the wimpy 3 oz. buffer in my PSA lower kit beating the rifle to a pulp. Luckily I had a heavy 5 oz buffer in my parts box so my worries were over.
Next I decided to price a new buffer in the 4 oz neighborhood on line. *(&%*&&^ they are expensive. Sheesh if I had a lathe I could turn one out in 20 minutes!
I took a spare 3 oz. buffer and drove the pin out. It had 3 weights inside. The weights were separated by rubber spacers. The weights were 1/2" diameter and .6" long. They were blued steel.
I found on Amazon a set of weights for sale that let you adjust your buffer to any desirable weight. Unfortunately the price was unbelievable too. I'm hoping that my buffer does not need to be toned down to the 4 oz range, but if it does I'm gonna try using lead shot for a filler in my 3 oz buffer.
Join the fight against excessive profits on buffers!!

 

[mcb]

Anything over the standard weight and at least some of the weights inside are a tungsten of some type or another. (ie H1 has one tungsten weight, H2 has two , H3 has all three) That is what drives up most of the cost. If the gun is gassed correctly you should not need the extra weight even with 7.62x39. All my AR use standard buffers even my 450 Bushmaster and 30 RAR. Heavy weight buffers are way too often simply a band-aid fix to an over-gassed gun.

 

[LoonWulf]

^ Agreed.
I'd save the money on buffer, and buy an adjustable gas block.
I'm about to order a few to have on hand. I actually have had no issues with the cheap ones besides the screw eroding. but unless you burn thru mags at a time that takes a while

 

[troy fairweather]

Yup a adjustable gas block will work out best, keep the recoil down to.

 

[MistWolf]

Don't be "Penny Wise and Pound Foolish". Get the H2 buffer and be done with it. Better still is the A5 RE assembly and the A5H2 buffer. The carbine buffer PSA uses has three steel weights and is simply too light no matter how your AR is gassed. The H2 is about 4 ozs which is the correct weight when using a carbine buffer.

The A5H2 buffer is about 5 ozs and has the benefit of using the rifle action spring. Of course, if an A5H2 buffer is used, an A5 RE must be used in place the standard carbine RE. If you need anything heavier than 5 ozs, you need to address gas flow issues.

The carbine weight buffer (all three weights being steel) is too light. The result is recoil that feels sharp no matter how the gas flow is tuned. I've tried it using an adjustable gas block and it does not work.

Shot filled buffers are false economy. You might get the buffer up to the right weight, but the reason the weights in the buffer float is to eliminate bolt bounce. Shot (and powdered tungsten) filled buffers do a poor job of damping bolt bounce.

 

[Pat Riot]

I am in the adjustable gas block camp. Granted, my experience building ARs is limited. I have assembled 5, but using an adjustable gas block in my last build was the perfect solution. My next ARs will get adjustable gas blocks.

 

[mcb]

Don't be "Penny Wise and Pound Foolish". Buy the right buffer. Don't fool around. Just get the H2 and be done with it. Better still is the A5 RE assembly and the A5H2 buffer. The carbine buffer PSA uses has three steel weights and is simply too light no matter how your AR is gassed. The H2 is about 4 ozs which is the correct weight when using a carbine buffer.

The A5H2 buffer is about 5 ozs and has the benefit of using the rifle action spring. Of course, if an A5H2 buffer is used, an A5 RE must be used in place the standard carbine RE. If you need anything heavier than 5 ozs, you need to address gas flow issues.

The carbine weight buffer (all three weights being steel) is too light. The result is recoil that feels sharp no matter how the gas flow is tuned. I've tried it using an adjustable gas block and it does not work.

Shot filled buffers are false economy. You might get the buffer up to the right weight, but the reason the weights in the buffer float is to eliminate bolt bounce. Shot (and powdered tungsten) filled buffers do a poor job of damping bolt bounce.

And yet every M4 carbine in military service uses a standard buffer. Bolt bounce is only an issue to be dealt with if you have the giggle switch.

Hx buffers are for band-aid fixes to over gassed guns and for tuning blow-back actions typical of pistol caliber AR's The best way to tune an AR is with proper gas regulation, buffer weight and spring stiffness are a distant second.

The A5 system is essentially an intermediate length buffer system. Longer than the standard M4 but shorter than that of the A2 rifle system. It utilizes a propitiatory receiver extension and buffer. It is as dependent on correct gas regulation as either of the other two system are.

 

[GunnyUSMC]

Odin Works makes an adjustable buffer that makes it easy to tune you buffer for your rifle.

 

[<*(((><]

I run a heavier buffer in my carbine gassed x39 specifically for increased time before the bolt unlocks to provide greater weight for peak pressure to subside. I do this mainly for better protection in the locking lugs of the bolt as they have been reduced in size for clearance of the x39 cartridge head. But it also aids in extraction as the peak pressure has subsided more before the extractor has to rip out the case. This in conjunction with lapping the upper receiver which helps ensure correct geometry lockup of the lugs.

For me with the compromises of some of the new AR “wildcat” cartridges I’m inclined to go heavier on the buffer even if I have an adjustable gas block. An adjustable gas block only controls how much gas gets to the carrier not when peak pressure will hit.

I run an H3 in my 16” carbine gassed x39 get a quality recoil spring to match.

 

[MistWolf]

The buffer used in issued M4s is the H2. Bolt bounce may not present any problems with the function of a semi auto AR, but it is a symptom of an undamped spike of energy being transferred from the carrier to the AR then reflected back to the carrier. This results in recoil being sharper than it needs to be. One result of using an H2 buffer is softer recoil.

mcb, as you point out, the proper function of an AR depends on proper gas flow along with the right buffer mass and spring rate. The lightweight carbine buffer is just too light. The A5 system isn't a magical solution that will fix an over gassed AR (the only way to fix an over gassed AR is to fix the gas flow), but it does soften recoil and according to tests, does slightly improve reliability over the H2.

 

[mcb]

The buffer used in issued M4s is the H2. Bolt bounce may not present any problems with the function of a semi auto AR, but it is a symptom of an undamped spike of energy being transferred from the carrier to the AR then reflected back to the carrier. This results in recoil being sharper than it needs to be. One result of using an H2 buffer is softer recoil.

mcb, as you point out, the proper function of an AR depends on proper gas flow along with the right buffer mass and spring rate. The lightweight carbine buffer is just too light. The A5 system isn't a magical solution that will fix an over gassed AR (the only way to fix an over gassed AR is to fix the gas flow), but it does soften recoil and according to tests, does slightly improve reliability over the H2.

M4s still have standard buffer. The upgraded M4A1 has an H2 buffer and a new heavier barrel with a different gas port diameter. This was done to slow the rate for fire in full-auto and reduce bolt bounce in full auto for reliability since the M4A1 has a Safe, Semi, Full-auto fire control instead of the Safe, Semi, 3-rd Burst fire control of the M4.

 

[LoonWulf]

Good info guys. I've built a fair number of ARs now, but haven't delved into the extremes too much.
I've run a heavy spring, heavy buffer combo in my .458socom
I've also run a gutted aluminum buffer, Iow mass bcg, and low weight recoil spring in my lightweight 556 build.....with an agb.

beyond that I've mostly used standard carbine buffers and springs. Adding an agb to that combo is a cheap way to tune the ar for function and feel.

 

[rbernie]

I’ve been building my own buffers for, well, forever:

https://www.kakindustry.com/ar-15-p...-tubes-and-parts/individual-buffer-tube-parts

Why should I pay $400 for a lightened bolt carrier, for example, when I can remove weight from the buffer by using aluminum spacers to achieve the same reciprocating weight and remove that weight from the end of the rifle where it has the most effect on balance, and do it for $20?

 

[someguy2800]

The combination I like best is to run an adjustable gas block and I dump all the weights out of the buffer.

The purpose of the buffer weights is to prevent bolt bounce, which is primarily a full auto problem, not a semi auto problem. The weights act as a dead blow hammer. With a properly tuned gas block running semi auto there is no purpose for extra buffer weight.

 

[H&R Glock]

The A5H2 buffer is about 5 ozs and has the benefit of using the rifle action spring. Of course, if an A5H2 buffer is used, an A5 RE must be used in place the standard carbine RE. If you need anything heavier than 5 ozs, you need to address gas flow issues.

Hey Mistwolf, you are snowing me with abbreviations. What is an "A5 RE"??????????
I am relatively new to the AR club and get lost quickly especially with all the new terms. I had to look up AGB and quickly figured it was an adjustable gas block.
Have sympathy for this newbee!

 

[GunnyUSMC]

I’ve been building my own buffers for, well, forever:

https://www.kakindustry.com/ar-15-p...-tubes-and-parts/individual-buffer-tube-parts

Why should I pay $400 for a lightened bolt carrier, for example, when I can remove weight from the buffer by using aluminum spacers to achieve the same reciprocating weight and remove that weight from the end of the rifle where it has the most effect on balance, and do it for $20?

$400 for a lightened BCG!
You need to learn where to shop.

 

[LoonWulf]

Hey Mistwolf, you are snowing me with abbreviations. What is an "A5 RE"??????????
I am relatively new to the AR club and get lost quickly especially with all the new terms. I had to look up AGB and quickly figured it was an adjustable gas block.
Have sympathy for this newbee!

RE in this case means reciever extension, or buffer tube.

 

[LoonWulf]

Odin Works makes an adjustable buffer that makes it easy to tune you buffer for your rifle.

I’ve been building my own buffers for, well, forever:

https://www.kakindustry.com/ar-15-p...-tubes-and-parts/individual-buffer-tube-parts

Why should I pay $400 for a lightened bolt carrier, for example, when I can remove weight from the buffer by using aluminum spacers to achieve the same reciprocating weight and remove that weight from the end of the rifle where it has the most effect on balance, and do it for $20?

those build a buffer kits are neat! one more thing to tinker with.....

 

[js8588]

My formula for a reliable AR build has been:
Quality but overgassed/aggressively gassed barrel (Daniel Defense/Noveske/BCM/Anything made by FN), Rifle length receiver extension/buffer (I vastly prefer fixed stocks. I'm 6'2. I'm going to keep an adjustable stock at no shorter than A1 length anyway), & an enhanced buffer spring (Tubbs flatwire or Strike Industries are now my go-to. SpringCo & Damage Industries are good too but they rust easily unless well greased).

I don't like adjustable gas blocks because added complexity in my mind introduces another possible failure point.

My ARs run everything from bulk cheapo 223 to mil spec 556 with no issues & c'mon, it's 556. There's no recoil to begin with.

 

[rbernie]

You need to learn where to shop.

Find me a lightweight / low mass AR10 carrier for less than $250, and I'll be forever grateful!

 

[LoonWulf]

Find me a lightweight / low mass AR10 carrier for less than $250, and I'll be forever grateful!

cheater! you didn't say ar10

 

[d2wing]

I run a heavier buffer in my carbine gassed x39 specifically for increased time before the bolt unlocks to provide greater weight for peak pressure to subside. I do this mainly for better protection in the locking lugs of the bolt as they have been reduced in size for clearance of the x39 cartridge head. But it also aids in extraction as the peak pressure has subsided more before the extractor has to rip out the case. This in conjunction with lapping the upper receiver which helps ensure correct geometry lockup of the lugs.

For me with the compromises of some of the new AR “wildcat” cartridges I’m inclined to go heavier on the buffer even if I have an adjustable gas block. An adjustable gas block only controls how much gas gets to the carrier not when peak pressure will hit.

I run an H3 in my 16” carbine gassed x39 get a quality recoil spring to match.

This. Heavier buffers slow down the bolt giving more time for the chamber pressure to drop for better extraction and save on extractor parts. Also it slightly increases dwell time for more reliable operation. However as stated you can reduce bolt speed with an adjustable gas block.

 

[lysanderxiii]

And yet every M4 carbine in military service uses a standard buffer. Bolt bounce is only an issue to be dealt with if you have the giggle switch.

M4s still have standard buffer. The upgraded M4A1 has an H2 buffer and a new heavier barrel with a different gas port diameter. This was done to slow the rate for fire in full-auto and reduce bolt bounce in full auto for reliability since the M4A1 has a Safe, Semi, Full-auto fire control instead of the Safe, Semi, 3-rd Burst fire control of the M4.

NOPE.

They all (both M4 and M4A1) use an H2 at this point.

The stock numbers for all carbine buffers other than P/N 13004468 (H2 weight), are coded "non-procurable, use alternate NSN". And the other NSN is 1005-01-522-0772, for the H2 buffer.

EDIT: The information in the second quote is dated. The Army approved the switch to the H2 buffer in the M4 back in 2010 or so.

FEDLOG info:

1005-01-231-3138
BUFFER ASSEMBLY,RECOIL
1005-01-231-3138 (1005012313138, 012313138)
Part Number (1 listing): 9390023
Summary
FSG 10 / FSC 1005
DEMIL: D
DEMIL INT: 1
HMIC: N
Date Created: 25 Apr 1986
Replacement NSN:
  1005-01-522-0772
Replacement Date: 14 Oct 2010
MSDS: None
Hazmat: None

 

[MistWolf]

Hey Mistwolf, you are snowing me with abbreviations. What is an "A5 RE"??????????
I am relatively new to the AR club and get lost quickly especially with all the new terms. I had to look up AGB and quickly figured it was an adjustable gas block.
Have sympathy for this newbee!

No problem!
- RE is "Receiver Extension", the proper name for what some call the "Buffer Tube".

- A5 is the designation of the receiver extension assembly VLTOR developed for the Marine Corps. The RE itself is not new. VLTOR used a longer RE design Armalite developed to allow an adjustable stock be used on the AR-10 using a carbine buffer. The AR-10 carrier is longer than an AR-15 carrier. When using a carbine RE on an AR-10, a shorter buffer is necessary to make room for the carrier. A shorter buffer means the spring coils have to be compressed tighter. Armalite designed an RE long enough to allow a carbine buffer to be used with the longer AR-10 carrier.

VLTOR realized they could use this AR-10 receiver extension with an intermediate buffer to allow a rifle spring to be used in an AR-15. In testing, it proved to be more reliable than a carbine RE/H2 assembly. (Not that the carbine RE/H2 assembly was problematic.)

In practice, I find the A5 RE assembly to be softer shooting than the H2. (Keep in mind the H2 is pretty smooth to begin with!) All my uppers, long or short, suppressed or unsuppressed, shoot smoothest and softest with the A5 RE. Next best is the H2. Smoothest and flattest recoil combination I have is a 20 inch upper with a Battlecomp compensator on the A5 lower.

 

[H&R Glock]

Thanks! Mistwolf!
It's gonna be a long time and more money before I get to own a rifle length RE.
sifting thru all the opinions ventured here I feel the 3 oz buffer will suffice, but my gut feeling is the H2 will give the gun a longer life and maybe a milder recoil.
I checked my other 7.62x39 AR and it has a 3.2 oz buffer. (The one PSA supplied with the lower kit.) It works fine, but when I first shot it, the increased recoil was greater than expected. Far from being painful, but noticeable compared to 5.56.
I can't wait till this huge covering of snow is gone so I can live at the range again. My first experiments will be with the H2 weight.
Yeah .............. I called it a buffer tube too!
Thank you all for your input to a beginners misunderstanding about the gas system/buffer system science. Now I have become dangerous?