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AR-15. Buffers and springs and tuning. Login/Join 
W07VH5
Picture of mark123
posted
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?
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
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You're looking for a solution to a problem that doesn't exist. If it runs, run it
 
Posts: 1792 | Location: Oregon | Registered: September 25, 2001Reply With QuoteReport This Post
W07VH5
Picture of mark123
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I’m just trying to learn without making too many mistakes.
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
Sigforum K9 handler
Picture of jljones
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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.




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"It's a bold strategy, Cotton. Let's see if it works out for them"



 
Posts: 37016 | Location: Logical | Registered: September 12, 2004Reply With QuoteReport This Post
Peace through
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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.
 
Posts: 106921 | Registered: January 20, 2000Reply With QuoteReport This Post
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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.





11 years to retirement! Just waiting!
 
Posts: 6147 | Location: Maryland | Registered: August 10, 2009Reply With QuoteReport This Post
Tupperware Dr.
Picture of GCE61
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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
 
Posts: 3533 | Registered: December 28, 2008Reply With QuoteReport This Post
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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?
 
Posts: 72 | Location: Minnesota | Registered: January 18, 2022Reply With QuoteReport This Post
W07VH5
Picture of mark123
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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.
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
W07VH5
Picture of mark123
posted Hide Post
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. Smile

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.
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
W07VH5
Picture of mark123
posted Hide Post
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.
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
quarter MOA visionary
Picture of smschulz
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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.
 
Posts: 22740 | Location: Houston, TX | Registered: June 11, 2006Reply With QuoteReport This Post
delicately calloused
Picture of darthfuster
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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.



You’re a lying dog-faced pony soldier
 
Posts: 29507 | Location: Highland, Ut. | Registered: May 07, 2008Reply With QuoteReport This Post
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Picture of 92fstech
posted Hide Post
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.
 
Posts: 8193 | Location: In the Cornfields | Registered: May 25, 2006Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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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.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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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.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
W07VH5
Picture of mark123
posted Hide Post
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.
 
Posts: 45287 | Location: Pennsyltucky | Registered: December 05, 2001Reply With QuoteReport This Post
Member
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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.
 
Posts: 436 | Location: people republic of Crapachusettes | Registered: September 05, 2002Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
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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.
 
Posts: 14094 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
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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.
 
Posts: 7825 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
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