buffer weight

[montana]

Update: today I took the new Grendel out for its maiden voyage. I loaded up a pressure ladder of 97gAbsolute Hammers over A2520 powder. I ran 13 rounds getting up to 2788fps safely.

I kept adjusting the gas screw out until it was barely holding on but could not get the bolt to lock back on the empty mag.

Im using a Geissele carbine buffer assembly. I suspect the culprit is their "Super 42" buffer spring, is "15% stronger" than a standard carbine spring.

There are many variables that come into play with short stroke or under gas issues..Adjustable gas blocks leak more gas than standard gas blocks and certain adj gas blocks can be more problematic than others..I despise the bleed off types.. If the rifle's gas system runs perfect with a properly fitting standard gas block, using an adj gas block can be problematic.. Adding heavier recoil springs or improperly fitting parts that increase friction will only add to the problem..

[Koda]

There are many variables that come into play with short stroke or under gas issues..Adjustable gas blocks leak more gas than standard gas blocks and certain adj gas blocks can be more problematic than others..I despise the bleed off types.. If the rifle's gas system runs perfect with a properly fitting standard gas block, using an adj gas block can be problematic.. Adding heavier recoil springs or improperly fitting parts that increase friction will only add to the problem..

Im going to order a standard (milspec??) carbine buffer spring and see if that fixes the issue.
I think I have a spare lighter buffer too or I will order one with the spring.

Input welcome on that idea...

I hope I dont need to fix or replace the gas block....

[mtnlvr]

How did you align the gas block?

[Koda]

How did you align the gas block?

I didnt.
I bought the upper as a completed assembly.

[mtnlvr]

I guess I just assumed you biult the upper too. My bad.

There have been reports of undersized gas potrts, misaligned gas blocks, defective gas blocks, etc. You may have to dig into that if the spring doesn't solve it for you.

What brand is the upper?

[Koda]

I guess I just assumed you biult the upper too. My bad.

There have been reports of undersized gas potrts, misaligned gas blocks, defective gas blocks, etc. You may have to dig into that if the spring doesn't solve it for you.

What brand is the upper?

No worries, a lot build their own its a good question.

My upper is a Grendel Hunter, 20in bbl 8 twist.

[montana]

No worries, a lot build their own its a good question.

My upper is a Grendel Hunter, 20in bbl 8 twist.

Factory built does not mean built correctly.. QC problems can occur with any firearm or part.

[v4lu3s]

I ONLY run H2 or heavier buffers in all AR platform. The 2.9-3 oz buffer is less reliable all around and is not used im any military specification. These days I am doing new builds with Vltor A5/BCM Mk2/SOLGW Loyal/Forward Controls length systems. Most every AR is overgassed and I have had what looked like short strokes actually be under sprung under buffer systems where the bolt was slamming back bottoming out and then bouncing so hard that the catch is not getting it nor was it stripping the next round. I only see you then out when the bolt catch got broken off.

[montana]

I ONLY run H2 or heavier buffers in all AR platform. The 2.9-3 oz buffer is less reliable all around and is not used im any military specification. These days I am doing new builds with Vltor A5/BCM Mk2/SOLGW Loyal/Forward Controls length systems. Most every AR is overgassed and I have had what looked like short strokes actually be under sprung under buffer systems where the bolt was slamming back bottoming out and then bouncing so hard that the catch is not getting it nor was it stripping the next round. I only see you then out when the bolt catch got broken off.

The heavier buffers were developed to slow carrier velocity and prevent bolt bounce on full auto..The H 1 was developed to slow carrier velocity on the M4 platform ( allowed more time for the magazine to push the next cartridge into place) and the H2 was developed to stop full auto bolt bounce on the heavier barreled M4A1..The H3 buffer was developed for the now defunct firing port weapon..

With an adj gas block, heavier buffers are completely unnecessary in any semi auto carbine AR if the rifle is well maintained..

Heavier buffers on an over gassed semi auto AR rifle is a band aid and not a cure..Even with heavier buffers, the over gassed system will pound on the firing pin retaining pin and is hard on gas rings..

If the rifle is not going to have an adj gas block, then I will use a heavier spring with a lighter buffer and will only use the heavier buffers as a last resort..

The more reciprocating mass, the more felt recoil..

I personally don't care for the Vltor A5 system and use only the standard carbine length system..

A lot of different opinions in AR world..

[Happy2Shoot]

I use the Xtra-Heavy buffer 8.5oz from heavybuffers.com for a 8.5" 5.56 pistol that I shoot suppressed.

It is smooth, recoil is much improved, and double-taps at 25 yards on a 2 second rotating target are easy. It has an adjustable gas block, but that wasn't enough. I set the gas block to lock back the BCG on an empty mag with one extra click open for a margin of error when dirty or cold or both. With the standard buffer weight I was getting gassed out and my bolt speed was too fast. It would jam on average once per magazine. Usually the jam was a new round wedged in with the spent round in front of the chamber.

If your heavy buffer isn't "bottoming out" on the back of your buffer tube the the extra weight will help with felt recoil. The low mass buffer smacking the back end of the buffer tube is a big problem for felt recoil. Also, the low mass buffers fully compress the spring giving you full spring return at full speed. A high mass buffer may only compress the spring 75%. Given the same (or less) spring compression, a higher mass object will return slower than a lower mass object.

I use their 6.5oz buffer for my 12.5" 5.56 and 6.5 Grendel pistols.

[v4lu3s]

The heavier buffers were developed to slow carrier velocity and prevent bolt bounce on full auto..The H 1 was developed to slow carrier velocity on the M4 platform ( allowed more time for the magazine to push the next cartridge into place) and the H2 was developed to stop full auto bolt bounce on the heavier barreled M4A1..The H3 buffer was developed for the now defunct firing port weapon..

With an adj gas block, heavier buffers are completely unnecessary in any semi auto carbine AR if the rifle is well maintained..

Heavier buffers on an over gassed semi auto AR rifle is a band aid and not a cure..Even with heavier buffers, the over gassed system will pound on the firing pin retaining pin and is hard on gas rings..

If the rifle is not going to have an adj gas block, then I will use a heavier spring with a lighter buffer and will only use the heavier buffers as a last resort..

The more reciprocating mass, the more felt recoil..

I personally don't care for the Vltor A5 system and use only the standard carbine length system..

A lot of different opinions in AR world..

The lighter buffers were developed as a cost-cutting measure for the civilian Market. And heavier buffers do not create or have anything to do with heavier recoil they reduce recoil by having more mass because it slows the cyclic rate, and the buffer weight moves slower because the laws of physics. When you impart the same energy to a heavyweight versus a lightweight the lightweight always moves much faster. A standard spring and a 3 oz buffer is far more likely to bottom out in a Carbine length receiver extension and that is where you will definitely feel more recoil.

An adjustable gas block is also a Band-Aid for a poorly balanced system. The system was designed to be over gassed for reliability, but the system was also designed around a four to five and a half ounce of buffer from the get-go.

If you look at a military M4 they run a heavier buffer than the 3-oz civilian buffer. With a carbine length gas system with a heavy bolt carrier group. They are over gas but they are reliable.

Obviously it's the internet but I've spent 15 years building ARs as a hobby. The only thing I've learned through that is the more I learn the more there is to know so I finally recently went and took a certified armorers course from Sons of Liberty Gun Works and learned more in the first 4 hours that I had in the past 15 years.

[biodsl]

If the rifle is not going to have an adj gas block, then I will use a heavier spring with a lighter buffer and will only use the heavier buffers as a last resort..

A standard spring and a 3 oz buffer is far more likely to bottom out in a Carbine length receiver extension and that is where you will definitely feel more recoil.

Then you agree with Montana; a stronger spring is better approached than a heavier buffer?

[montana]

The lighter buffers were developed as a cost-cutting measure for the civilian Market. And heavier buffers do not create or have anything to do with heavier recoil they reduce recoil by having more mass because it slows the cyclic rate, and the buffer weight moves slower because the laws of physics. When you impart the same energy to a heavyweight versus a lightweight the lightweight always moves much faster. A standard spring and a 3 oz buffer is far more likely to bottom out in a Carbine length receiver extension and that is where you will definitely feel more recoil.

An adjustable gas block is also a Band-Aid for a poorly balanced system. The system was designed to be over gassed for reliability, but the system was also designed around a four to five and a half ounce of buffer from the get-go.

If you look at a military M4 they run a heavier buffer than the 3-oz civilian buffer. With a carbine length gas system with a heavy bolt carrier group. They are over gas but they are reliable.

Obviously it's the internet but I've spent 15 years building ARs as a hobby. The only thing I've learned through that is the more I learn the more there is to know so I finally recently went and took a certified armorers course from Sons of Liberty Gun Works and learned more in the first 4 hours that I had in the past 15 years.

The original CAR15 used by SOG during the Vietnam war used the standard buffer..It was used in the first civilian Colt carbine.. I gave the reasons for the increase of buffer weights used in the M4/M4A1 and cost cutting was not one of them..I tried the VltorA5 on my daughters rifle and she was not impressed and neither was I.. I returned it back to a standard receiver extension..

Heavier buffers do create more recoil impulse, which is why competition rifles use lighter carriers ( less reciprocating mass equals less recoil).. The caveat is the gas (ammunition type) has to match the recoiling weight/force being used..If an AR is over gassed, a heavier buffer is beneficial if there is no method to adjust the gas, but it is a band aide approach when it is possible to adjust the gas/ammunition to the rifle.. I have found it is better to increase recoil spring strength with a standard buffer than to use a heavier buffer with a standard recoil spring to mitigate recoil impulse..

An adjustable gas block will only restrict the available gas, not increase it.. The difference between military rifles and civilian rifles is the plethora of different ammunition being used by civilians compared to the military's smaller set of ammunition standards..



I'm not going to despair SOLGW or anyone else..I have great respect for Mike Mihalski SOLGW, Chad ( who I met personally at a Colt armorers class and call him friend) from SOTAR, Caleb from Brownells and others, but I don't agree with everything they say..By the way, none of these gentlemen agree 100 percent with each other..That said, I will take the Pepsi challenge with my rifles against anyone when it comes to recoil management..

Different builds require different approaches when building an AR rifle, whether it is reliability, accuracy, recoil management or combinations of each..Choose your poison!

[LRRPF52]

I ONLY run H2 or heavier buffers in all AR platform. The 2.9-3 oz buffer is less reliable all around and is not used im any military specification. These days I am doing new builds with Vltor A5/BCM Mk2/SOLGW Loyal/Forward Controls length systems. Most every AR is overgassed and I have had what looked like short strokes actually be under sprung under buffer systems where the bolt was slamming back bottoming out and then bouncing so hard that the catch is not getting it nor was it stripping the next round. I only see you then out when the bolt catch got broken off.

[montana]

The primary purpose of the different buffer weights are to correspond with the barrel mass to counter carrier-bounce in FULL or BURST Automatic fire modes.

The main reason for the added weight (H buffer) in the M4 was the adoption of the M855 bullet that had a different ogive than the M193 bullet that was causing feed malfunctions, not bolt bounce..

The original fix was the addition of feed ramps in the upper receiver.. Colt then added a tungsten weight to slow the carrier down to allow the magazine time to present the cartridge for proper feeding..Colt maintained the feed ramps as a redundancy for proper feeding and to keep the M4 TDP as Colt intellectual property when the government tried to claim ownership..

https://youtu.be/DYf-MLMODhA?si=zdMg_5I9DaHqUGYc&t=755