H2 or H3 Buffer for 16" Mid-Length AR with Suppressor


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Captains1911
November 16, 2014, 03:54 PM
I'm currently running an H buffer in my 16" middy, however I would like to try something heavier for suppressor use to reduce potential increased wear. I understand the better solution is an adjustable gas block, however I do not wish to mess with that at this time. I'm just unsure if I should order an H2 or H3, so any input would be appreciated.

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Tomac
November 16, 2014, 06:10 PM
Too many variables for a set answer (gas port size? buffer spring strength? etc). Conventional wisdom is to run the heaviest buffer that your rifle will cycle reliably with and lock back on w/the weakest ammo you normally use.
HTH...
Tomac

Onmilo
November 16, 2014, 06:12 PM
^^^THIS^^^

HKGuns
November 17, 2014, 09:48 PM
You really need to provide more details on your setup for a more precise answer. What barrel? What RE, with what spring?

My standard answer is to upgrade to a VLTOR A5 RE and spring with an H3 buffer, but depending on your exact setup you might need an H2. After doing this upgrade, experiment with some lighter loads, like PMC bronze and see if your bolt locks back on the last round or if you have feeding issues.

This assumes you are shooting unsuppressed.

Captains1911
November 17, 2014, 10:20 PM
You really need to provide more details on your setup for a more precise answer. What barrel? What RE, with what spring?

My standard answer is to upgrade to a VLTOR A5 RE and spring with an H3 buffer, but depending on your exact setup you might need an H2. After doing this upgrade, experiment with some lighter loads, like PMC bronze and see if your bolt locks back on the last round or if you have feeding issues.

This assumes you are shooting unsuppressed.

It's a 16" barrel with a mid length gas system, all BCM internals, including BCG, CAR extension and spring.

I am referring to shooting suppressed, hence the title of the thread...

HKGuns
November 18, 2014, 11:34 AM
hence the title of the thread...

Must have read right past that....Brand of barrel would be of help so as to discern gas port size. However, suppressed you're likely safe with H3 or potentially 4 depending on gas port size in your barrel.

Captains1911
November 18, 2014, 11:40 AM
BCM barrel, 16", mid-length. I went ahead and ordered an H3 buffer to try out. Thanks.

HKGuns
November 18, 2014, 09:26 PM
While I don't own one, the BCM appears to have a built to spec gas port. The H3 will likely work great for you.

Captains1911
January 11, 2015, 02:06 PM
Just an update, the rifle runs 100% with the H3 buffer, both with and without the suppressor, shooting Federal XM193 ammo.

HKGuns
January 13, 2015, 10:44 PM
Try PMC Bronze as the acid test for weaker ammo. If it runs with that it will likely run with anything. Congrats.

MistWolf
January 13, 2015, 10:48 PM
Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money

Captains1911
January 14, 2015, 08:57 AM
Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money
Really. Care to elaborate?

wally
January 14, 2015, 10:27 AM
Try PMC Bronze as the acid test for weaker ammo. If it runs with that it will likely run with anything.

I thought Wolf steel cased was the "gold standard" for this :)

Warp
January 14, 2015, 12:48 PM
Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money

You could not be more wrong.

There is no "tuning" necessary for it to run. There are different buffer weight you can use (really the one and only variable here) with mutiple weights all working, but some maybe being easier on the rifle (less carrier bounce, etc) than others.

Even if it is "over gassed" and does not have an H2 or H3 buffer, or whatever, any decent rifle should still run just fine with a suppressor. Though of course I'd still like to run a heavier buffer to ease the wear/tear, in theory anyway.

C-grunt
January 14, 2015, 02:34 PM
My Colt 6920 ran fine suppressed when stock. Now with a VLTOR A5 on it runs smoother and still very reliable.

HKGuns
January 14, 2015, 06:28 PM
I thought Wolf steel cased was the "gold standard" for this

I've honestly never shot the stuff out of any of my rifles, so you might be 100% correct. PMC Bronze is the softest shooting stuff I've ever used. Good call if it is lighter than PMC Bronze.

I can understand where MIST is coming from, but I prefer not to mess with gas blocks on my rifles, as that requires more fiddling than I typically care to mess with given the time I don't have normally to do this stuff. Still I don't consider it a waste of time or money.

Personal preference and the extent to which you're willing to mess with an off the shelf upper are a significant factor for me.

MistWolf
January 14, 2015, 08:04 PM
Really. Care to elaborate?
You could not be more wrong

Running a suppressor increases "dwell" time significantly as it slows the exit of gas from the rifle. The result is more gas flows through the gas tube for a longer time, gassing the shooter even with increased reciprocating mass. The only way to reduce the gas flowing through the gas tube is to restrict gas flow by using a smaller gas port or using an adjustable gas block.

With a Syrac or SLR adjustable gas block, it's simple matter to adjust gas. Put one round in the mag and adjust the block until the carrier locks back. Sometimes the block will need to be opened a couple clicks more for fully reliable function. Not only will the rifle shoot reliably with softer recoil, gas to the face is greatly reduced

Warp
January 14, 2015, 10:14 PM
Running a suppressor increases "dwell" time significantly as it slows the exit of gas from the rifle. The result is more gas flows through the gas tube for a longer time, gassing the shooter even with increased reciprocating mass. The only way to reduce the gas flowing through the gas tube is to restrict gas flow by using a smaller gas port or using an adjustable gas block.

Okay. But this statement:

Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money

Is simply incorrect.

Any decent AR carbine will run with a suppressor and without an adjustable gas block.

There are multiple posters in this thread who run or have run otherwise stock carbines (gas system/buffer system wise) with suppressors and God only knows how many other people who have done the same thing. They work, plain and simple.

MistWolf
January 14, 2015, 11:10 PM
An AR carbine will generally run with a suppressor with a simple buffer swap but the issues with over gassing that make the rifle unpleasant to shoot will remain. That does not meet the definition of "TUNED to run". You can waste your time trying to make changes that do not address the real problems, or you can hit the Easy Button and use an adjustable gas block which will. It's your rifle, it's your money

C-grunt
January 15, 2015, 04:46 AM
I thought Wolf steel cased was the "gold standard" for this :)
Wolf has problems because it steel cased and can have problems with extraction.

PMC Bronze is light loaded. Someone did a thread where they chronoed a bunch of different ammo and PMC Bronze was the slowest by a good margin. If I remember correctly Wolf is actually loaded kind of hot.

EDIT: Not the exact thread I was looking for but you can see PMC is pretty light.


http://www.ar15.com/archive/topic.html?b=3&f=16&t=505425

Captains1911
January 15, 2015, 08:53 AM
An AR carbine will generally run with a suppressor with a simple buffer swap but the issues with over gassing that make the rifle unpleasant to shoot will remain. That does not meet the definition of "TUNED to run". You can waste your time trying to make changes that do not address the real problems, or you can hit the Easy Button and use an adjustable gas block which will. It's your rifle, it's your money
What you consider "the easy button" for other people requires the purchase of special tools and parts that puts the cost somewhere in the $150 - $200 range. Not everybody is so inclined to start taking apart an upper that was put together by people who know a lot more about it. For those people, the "easy button" involves just using a heavier buffer and/or spring to help offset the increase rate of cycling resulting from the increase in gas pressure. Your statement that this is waste of time and money is quite silly. My rifle runs with the can and the $35 H3 buffer, and by pure physics it is cycling slower with the heavier buffer, so what time and money have I wasted exactly?

Art Eatman
January 15, 2015, 10:20 AM
A local Class 3 FFL here sells/installs several cans each year for ARs. He test fires all of them. Various barrel lengths and all that. Doesn't seem to be any problem in having them "run", these last few years.

The bullet is beyond the gas port when it enters the can. There is an immediate pressure drop. Hard to see any mechanism that would affect the gas pressure in the operating system.

MistWolf
January 17, 2015, 02:53 AM
The bullet is out of the barrel completely before the gas system charges (the rifle actually operates on residual pressure). However, the suppressor slows the rate at which the rifle vents- that's one of the ways it reduces the sound. Because of this, pressure is higher so more gas flows through the port bringing the expansion chamber up to operating pressure quicker and increases carrier acceleration.

It also means that there is more gas being dumped overboard through the carrier vents and more gas from the gas tube after the gas key separates from it. This results in more gas to the face.

While a heavier buffer will slow the carrier acceleration, it does nothing to reduce the volume of gas venting from the carrier and gas tube. To do that, you need to reduce flow from the gas port. That means either changing to a barrel with a smaller gas port or getting an adjustable gas block

Warp
January 17, 2015, 11:55 AM
The bullet is out of the barrel completely before the gas system charges (the rifle actually operates on residual pressure). However, the suppressor slows the rate at which the rifle vents- that's one of the ways it reduces the sound. Because of this, pressure is higher so more gas flows through the port bringing the expansion chamber up to operating pressure quicker and increases carrier acceleration.

It also means that there is more gas being dumped overboard through the carrier vents and more gas from the gas tube after the gas key separates from it. This results in more gas to the face.

While a heavier buffer will slow the carrier acceleration, it does nothing to reduce the volume of gas venting from the carrier and gas tube. To do that, you need to reduce flow from the gas port. That means either changing to a barrel with a smaller gas port or getting an adjustable gas block

Perhaps it would have been better not say Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money and instead say something like 'an adjustable gas block will allow you to reduce gas to the face'.

Because, as we have covered, they run perfectly fine without adjustable gas blocks (I would wager the majority, probably the vast majority, of suppressed AR shooters don't use adjustable gas blocks)

gotigers
January 18, 2015, 01:03 AM
I have an spikes ST-T2 buffer with my SBR and silencerco specwar. The adjustable gas block is more important for this, IMHO. The adjustable gas block is so much easier to deal with than guessing which buffer. My suppressed SBR and my 3 gun AR run perfectly with adjustable gas blocks. Both have totally different buffer systems. One is a heavy buffer and carrier, the SBR and one has a low mass carrier and buffer, the 3 gun AR.

Most suppressed AR owners that I know personally have adjustable gas blocks when the host is a full time host. Like my SBR is my HD AR. It always has the can mounted.

Setting up the gas blocks was a one time trip to the range. I haven't needed to adjust since.

MistWolf
January 18, 2015, 12:59 PM
Perhaps it would have been better not say Trying to tune an AR carbine to run suppressed without an adjustable gas block is a waste of time and money and instead say something like 'an adjustable gas block will allow you to reduce gas to the face'.

Because, as we have covered, they run perfectly fine without adjustable gas blocks (I would wager the majority, probably the vast majority, of suppressed AR shooters don't use adjustable gas blocks)

An AR that's gassing it's shooter is NOT running perfectly fine. It's over-gassed

I have an spikes ST-T2 buffer with my SBR and silencerco specwar. The adjustable gas block is more important for this, IMHO. The adjustable gas block is so much easier to deal with than guessing which buffer. My suppressed SBR and my 3 gun AR run perfectly with adjustable gas blocks. Both have totally different buffer systems. One is a heavy buffer and carrier, the SBR and one has a low mass carrier and buffer, the 3 gun AR.

Most suppressed AR owners that I know personally have adjustable gas blocks when the host is a full time host. Like my SBR is my HD AR. It always has the can mounted.

Setting up the gas blocks was a one time trip to the range. I haven't needed to adjust since.

gotigers
January 18, 2015, 10:50 PM
To add to my last post: My SBR with can does not vent in my face via the charging handle. If it is venting, I haven't noticed it.

Edit: This is my experience. Each gun will have different issues. Once you throw together an SBR with a can, everything becomes important: gas port diameter, dwell time, cycle speeds, bolt bounce, buffer weight, muzzle device, etc. Each gun will have different issues, if any. My experience might not be the norm. This AR with and can works well. My next one might not.

I do know owners of ARs with cans that have complained about venting.

Zerodefect
January 18, 2015, 11:15 PM
Get the H3. And remove a weight or two from it to bring it down to a H2. Add the weight back if you need to get your ejection pattern back to 3:30-4:00. If it was a carbine I'd go straight to a adj gas block. But it's a middy and maybe ok.

You can also cut the barrel down to 14.7" to reduce gas. I've always like the long dwell time of carbines with small gas ports or reduced adj gas blocks. More flow time, less pressure. Middy 14.5 and rifle 18.5 are really popular right now because of the softer recoil.

Warp
January 18, 2015, 11:24 PM
Get the H3. And remove a weight or two from it to bring it down to a H2. Add the weight back if you need to get your ejection pattern back to 3:30-4:00. If it was a carbine I'd go straight to a adj gas block. But it's a middy and maybe ok.

You can also cut the barrel down to 14.7" to reduce gas. I've always like the long dwell time of carbines with small gas ports or reduced adj gas blocks. More flow time, less pressure. Middy 14.5 and rifle 18.5 are really popular right now because of the softer recoil.

After you file a Form 1 and receive the stamp for an SBR and engrave the lower of course

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