AR-15. Buffers and springs and tuning.

December 24, 2023, 08:38 PM

mark123

I’ve got an 11.5” SBR and in my recent reading I understand that an SBR should have a heavier buffer. H2 is apparently rather common. However, I used a milspec LPK and just threw in the buffer that came with it because I wasn’t exactly aware of which buffer was included and i also wasn’t certain that I may need to change the configuration. I just assumed it was an H1.

The gun runs well and ejects properly but I was just farting around and weighed the buffer. It’s a 3 oz. Which isn’t an H1 it’s a standard carbine buffer.

If the gun runs fine, is there any reason to experiment with heavier buffers? Are the benefits noticeable or subtle or nonexistent?

December 24, 2023, 09:04 PM

SIG228

You're looking for a solution to a problem that doesn't exist. If it runs, run it

December 24, 2023, 09:17 PM

mark123

I’m just trying to learn without making too many mistakes.

December 24, 2023, 09:48 PM

jljones

Yes. Experiment away.

Buffers and springs can optimize recoil patterns, and even reduce wear and tear further. Worst is you’re out 30-40 bucks. But, look at the experience you gain by doing it yourself.

December 24, 2023, 10:02 PM

parabellum

There are a lot of factors. I'm assuming that the barrel is chambered for 5.56.

Do you plan on running it mainly with .223 ammo, or 5.56? 5.56 is higher pressure- on average- by about 3000 PSI IIRC.

The size of the gas port is a factor as well. Your barrel probably has a larger gas port to compensate for the brief dwell time due to the gas port being closer to the muzzle.

If your rifle functions consistently with any buffer, you're probably OK with an H2 buffer. The philosophy surrounding buffer choice is to use the heaviest buffer your rifle will function with consistently.

Lighter buffers will work but if the buffer is too light, your buffer, action spring and receiver extension will take an unnecessary pounding. A heavier buffer will slow down the extraction and feeding parts of the firing cycle and heavier buffers will aid in preventing bolt bounce (a slight rebounding of the bolt and carrier as the bolt closes on a freshly-fed round). This is something you don't need to be concerned about in semi-auto fire. Bolt bounce is a factor only with full-auto fire.

If a buffer is too heavy, you may get failures to extract or weak ejection but I doubt you'll have this problem.

I don't have any 11.5" uppers, but here's the starting point for me with what I do have:

For 16" barrels with carbine-length gas systems, I assume that the upper is slightly over-gassed, as the dwell time is longer than that of Stoner's design, and therefore, I use H2 buffers.

For 16" barrels with a mid-length gas system, dwell time is the same as Stoner's 20" barrel design, and thus, about optimal, and therefore, I use an H buffer.

For 14.5" barrels with carbine-length gas systems- again, dwell time is near optimal, and therefore, I use an H Buffer.

For using a suppressor on any of the above, I increase buffer weight by one increment. For example, on a 16" carbine-length gas system with a suppressor attached, I use an H3 buffer.

If you can shoot your rifle outside, you can get an idea of how far brass is being thrown (not possible on an indoor range with the usual narrow lanes). If your brass is being thrown a long way, increase the buffer weight.

I don't see standard carbine buffers in rifles these days. Again, a 16" barrel with a carbine length gas system will have greater dwell time, and you wouldn't want to use the carbine buffer for such a setup- although it would work.

In the case of your 11.5" barrel, the dwell time is shorter than optimal, and perhaps this is why the manufacturer included a carbine buffer, but, yes, I've heard the same thing you heard: For such a setup, use an H2 buffer. I imagine these short barrels have enlarged gas ports to compensate for the short dwell time but that's just a guess on my part.

Personally, I don't get fancy with action springs. I may alter the buffer weight but I stick with milspec-style action springs.

This should give you a general idea. Shoot your rifle where you can observe how the brass ejects and go from there.

December 24, 2023, 10:32 PM

OttoSig

Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

December 25, 2023, 06:28 AM

GCE61

quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I have a JP in one of my carbine Di guns and it runs smooth, no issues

December 25, 2023, 07:37 AM

Eaganite

quote:
Originally posted by parabellum:

For 16" barrels with carbine-length gas systems, I assume that the upper is slightly over-gassed, as the dwell time is longer than that of Stoner's design, and therefore, I use H2 buffers.

If you can shoot your rifle outside, you can get an idea of how far brass is being thrown (not possible on an indoor range with the usual narrow lanes). If your brass is being thrown a long way, increase the buffer weight.

This has me curious, what distance would be considered a long way? What would be optimal distance?

December 25, 2023, 07:49 AM

mark123

quote:
Originally posted by parabellum:
There are a lot of factors. I'm assuming that the barrel is chambered for 5.56.

Do you plan on running it mainly with .223 ammo, or 5.56? 5.56 is higher pressure- on average- by about 3000 PSI IIRC.

The size of the gas port is a factor as well. Your barrel probably has a larger gas port to compensate for the brief dwell time due to the gas port being closer to the muzzle.

If your rifle functions consistently with any buffer, you're probably OK with an H2 buffer. The philosophy surrounding buffer choice is to use the heaviest buffer your rifle will function with consistently.

Lighter buffers will work but if the buffer is too light, your buffer, action spring and receiver extension will take an unnecessary pounding. A heavier buffer will slow down the extraction and feeding parts of the firing cycle and heavier buffers will aid in preventing bolt bounce (a slight rebounding of the bolt and carrier as the bolt closes on a freshly-fed round). This is something you don't need to be concerned about in semi-auto fire. Bolt bounce is a factor only with full-auto fire.

If a buffer is too heavy, you may get failures to extract or weak ejection but I doubt you'll have this problem.

I don't have any 11.5" uppers, but here's the starting point for me with what I do have:

For 16" barrels with carbine-length gas systems, I assume that the upper is slightly over-gassed, as the dwell time is longer than that of Stoner's design, and therefore, I use H2 buffers.

For 16" barrels with a mid-length gas system, dwell time is the same as Stoner's 20" barrel design, and thus, about optimal, and therefore, I use an H buffer.

For 14.5" barrels with carbine-length gas systems- again, dwell time is near optimal, and therefore, I use an H Buffer.

For using a suppressor on any of the above, I increase buffer weight by one increment. For example, on a 16" carbine-length gas system with a suppressor attached, I use an H3 buffer.

If you can shoot your rifle outside, you can get an idea of how far brass is being thrown (not possible on an indoor range with the usual narrow lanes). If your brass is being thrown a long way, increase the buffer weight.

I don't see standard carbine buffers in rifles these days. Again, a 16" barrel with a carbine length gas system will have greater dwell time, and you wouldn't want to use the carbine buffer for such a setup- although it would work.

In the case of your 11.5" barrel, the dwell time is shorter than optimal, and perhaps this is why the manufacturer included a carbine buffer, but, yes, I've heard the same thing you heard: For such a setup, use an H2 buffer. I imagine these short barrels have enlarged gas ports to compensate for the short dwell time but that's just a guess on my part.

Personally, I don't get fancy with action springs. I may alter the buffer weight but I stick with milspec-style action springs.

This should give you a general idea. Shoot your rifle where you can observe how the brass ejects and go from there.

Thank you.

I run 5.56 in the ARs. And only shoot it outdoors as my range only allows pistol caliber indoors. It does chuck the cases a good distance, over past the next stall. I’ll measure it next time. It does eject at 4 o’clock so it seems it’s not over-gassed. I’ll pick up some H2 buffers and see how it affects the recoil pulse.

I appreciate the reply.

December 25, 2023, 07:52 AM

mark123

quote:
Originally posted by jljones:
Yes. Experiment away.

Buffers and springs can optimize recoil patterns, and even reduce wear and tear further. Worst is you’re out 30-40 bucks. But, look at the experience you gain by doing it yourself.

I suppose I should just buy some.

quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I have one and that’s why I started reading about buffer weights. I should have ordered the H2 version so it looks like I will have to order a couple tungsten weights.

December 25, 2023, 08:02 AM

mark123

quote:
Originally posted by GCE61:
quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I have a JP in one of my carbine Di guns and it runs smooth, no issues

I think OttoSig is asking if there’s any improvement. If there’s no change then it’s not worth switching out a perfectly good boingy spring and buffer. Of course, I’m a sucker for gimmicks like this and had to try it myself. Range report to follow in the future.

December 25, 2023, 09:11 AM

smschulz

quote:
f the gun runs fine, is there any reason to experiment with heavier buffers?

Not in my opinion, along with noting a proper ejection pattern.
An adjustable gas block is a handy companion.

December 25, 2023, 10:53 AM

darthfuster

quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I have one in one of my boutique builds. It works great and is quiet.

December 25, 2023, 12:48 PM

92fstech

quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I have one from a different manufacturer (can't remember who). It's smooth and quiet, and I like it in the range toy I have it installed in. From a function and reliability standpoint, I don't think it offers any benefit over a standard spring/buffer setup...if anything it introduces more potential failure points, although I've had no problems with it.

December 25, 2023, 06:16 PM

IndianaBoy

quote:
Originally posted by OttoSig:
Are the JP silent captured assemblies worth investing in?

I've never used one, figured it might be a good addition for my one most-used AR, not gonna outfit them all.

I use them on my match rifles. Worth it to me but it isn't an enormous difference.

December 25, 2023, 06:30 PM

IndianaBoy

The JP silent captive buffer is often misunderstood, IMHO.

It is less about noise, and more about perceived feel of the action cycling. A properly tuned AR with a JP captive buffer feels like a bolt action when you shoot it. It removes the ker-chunk feel of the action cycling. You might not notice that it is there, until it is gone.

December 26, 2023, 01:07 PM

mark123

quote:
Originally posted by IndianaBoy:
The JP silent captive buffer is often misunderstood, IMHO.

It is less about noise, and more about perceived feel of the action cycling. A properly tuned AR with a JP captive buffer feels like a bolt action when you shoot it. It removes the ker-chunk feel of the action cycling. You might not notice that it is there, until it is gone.

I just want to flatten out the recoil for follow ups. That was my reasoning for trying one.

December 26, 2023, 01:44 PM

Stinx

In My Colt 11.5 EPR I run a springco blue buffer spring and h2 buffer. My gun runs very well and the ejection pattern is right where it should be.

December 26, 2023, 07:24 PM

IndianaBoy

quote:
Originally posted by mark123:
I just want to flatten out the recoil for follow ups. That was my reasoning for trying one.

Adjustable gas block would be first and most significant step in accomplishing that.

A muzzle brake can also accomplish a lot in that respect, but with the downside of significantly more and louder muzzle blast, especially on a short barrel.

Adjustable gas blocks are a great way to tune an AR.

December 28, 2023, 11:26 AM

fritz

quote:
Originally posted by mark123:
I just want to flatten out the recoil for follow ups. That was my reasoning for trying one.

The best recoil reduction device is a good muzzle brake. 60-70% reduction in recoil, but with a noise increase of at least 10dB. The noise levels are quite unpleasant on an SBR.

Next is a good suppressor. 50-60% reduction in recoil, 20-30 dB decrease in noise. The recoil pulse is spread out a bit more with a can, whereas the pulse just stops immediately with a brake. Can downsides are cost and longer effective barrel length.

I find that most ARs that aren't using bunny-fart ammo work just fine -- if not better -- with a little heavier buffer. Not a huge difference, but it's there.

Adjustable gas blocks work in fine tuning. Except when they fail, and I've seen that occur in matches.

The JP silent capture buffer system is nice. I have them in 3 rifles, using H3 buffers. The sound difference is noticeable, given that our faces are right over the spring. The recoil pulse is a bit smoother with the JP -- some people notice it, others don't. I like the JP system for high volume shooting, such as big matches and extended training sessions. JP silent capture system definitely costs more than a heavier buffer.

Recoil reduction is discussed here and there with 223 AR15. Of course, the 223 round has one of the lowest recoil levels of any centerfire ammo. For a shooter with good technique, video analysis of recoil shows minimal sight picture disturbance from an AR15. The best test of how various devices affect AR15 recoil should be done on the clock, on multiple targets, from multiple positions. The "I kinda sorta think this helps" from a common range's bays mean little.