Buffer vs carrier weight?

[penguinofsleep]

Assuming some 6, 6.5, or 6.8mm based ar15 sized cartridge, supersonic + unsuppressed, and the same adjustable gas block, recoil spring, and buffer kit being used between the two options.

Is there any real difference between using a lightweight carrier and heavier buffer vs using a "normal" semi/auto weight carrier if the total weight of the reciprocating mass is the same?
Just as an example
- JP LMOS steel carrier + bolt = 8.8oz + h2 buffer ~4.7oz = 13.5 oz. h2 because I've seen them more frequently with 6.x mm builds vs other weights.
- semi carrier + bolt = 10.5oz + carbine buffer 3oz = 13.5oz.
It seems like lighter carrier + heavier buffer is more popular but not sure if this is just due to increased flexibility as changing buffers and/or weights cost less than a new carrier or if there's a more functional reason.

 

[TimK]

I’ve been down this rabbit hole. As far as I can tell from my testing, it’s the total mass of the system that matters. For example, I can’t discern any difference in accuracy, recoil, or reliability between a light BCG with heavy buffer and heavy BCG with light buffer If the total weight of the reciprocating mass of the system system is the same.

 

[bigjake83]

You're just canceling each other out and missing the entire point of each component.

 

[penguinofsleep]

Thanks.

Figured as much but noticed in the past that several builds on posted on various forums as well as various mfg all advised that I start with this as a base line for a 6.X mm build. Baseline explanation was “reliability” but when I asked why, no one really had an answer.

Settled on a different config eventually but just found the above curious.

 

[Evintos]

Thanks.

Figured as much but noticed in the past that several builds on posted on various forums as well as various mfg all advised that I start with this as a base line for a 6.X mm build. Baseline explanation was “reliability” but when I asked why, no one really had an answer.

Settled on a different config eventually but just found the above curious.

It seems like lighter carrier + heavier buffer is more popular but not sure if this is just due to increased flexibility as changing buffers and/or weights cost less than a new carrier or if there's a more functional reason.

It's because most people don't understand the timing aspects of the AR gas system and they rather not deal with having to troubleshoot cycling issues over email or phone or waste money having a customer ship a firearm in for "service." They'll give you a baseline to start off with so it's easier to deal with later if necessary and swapping buffers is easy.

From a functional perspective - if you're trying to remove reciprocating mass to tune for lowest recoil impulse, low mass carrier is typically the better way to go. You can only reduce buffer weight by so much (from H3 buffer to Car buffer is a difference of 2.4 to 2.6oz, excluding non-standard buffer configs). With low mass carriers, you can remove 2oz up to 6oz out of the system (depending on which low mass carrier and whether you're comparing a low mass BCG to a semi auto BCG or a full auto BCG).

With an AGB, you typically don't start off with a heavier buffer anyways. So the ability to reduce mass is essentially limited to BCG.

 

[TonyTheTiger]

You can only reduce buffer weight by so much (from H3 buffer to Car buffer is a difference of 2.4 to 2.6oz, excluding non-standard buffer configs).

Not necessarily. You can replace one or all of your weights with delrin or something. You can empty it completely. I have quite a few rifles that just have a delrin disk that sits in the end of the spring rather than an actual buffer. Weighs like .2oz.

 

[Evintos]

Not necessarily. You can replace one or all of your weights with delrin or something. You can empty it completely. I have quite a few rifles that just have a delrin disk that sits in the end of the spring rather than an actual buffer. Weighs like .2oz.

I would consider those non-standard configurations though.

 

[cas6969]

lol

But non standard weigh carriers aren't?

 

[penguinofsleep]

It's because most people don't understand the timing aspects of the AR gas system and they rather not deal with having to troubleshoot cycling issues over email or phone or waste money having a customer ship a firearm in for "service." They'll give you a baseline to start off with so it's easier to deal with later if necessary and swapping buffers is easy.
.....

Makes perfect sense and was kind of what I was expecting.


On a different note for everyone - asking to help expedite range time - is there an expected formula that can be followed if I want to reduce buffer weight and slightly reduce spring rate for a hopefully flatter shooting gun while maintaining about the same level of reliability and accuracy if the gas block is dialed down as well? Or am I just going to have to mess around with different combos of buffer weights, recoil spring rates, and gas block settings?
For the sake of simplicity - assume a variety of Hornady or some other similar big brand factory ammo that's probably loaded to work with a variety of guns, not handloads that are only optimized to barely run 100% in one particular rifle.

 

[Evintos]

lol

But non standard weigh carriers aren't?

Low mass carriers are non-standard configurations but the only carrier you really can modify in terms of mass is the JP VMOS. Mostly it's buy a low mass carrier, drop one in, check headspace (most people even skip this), and tune gas (although some don't even know that there's a gas or mass tuning requirement).

Modification of the buffer from standard weight configurations require a little more work than just dropping in a part and while there are benefits to taking buffer weight tuning to that next level and not to mention it being incredibly simple, most people won't do so. So for most people it's buy buffer in standard weights (Car, H1, H2, H3, A5s, etc.), drop them in.

Makes perfect sense and was kind of what I was expecting.


On a different note for everyone - asking to help expedite range time - is there an expected formula that can be followed if I want to reduce buffer weight and slightly reduce spring rate for a hopefully flatter shooting gun while maintaining about the same level of reliability and accuracy if the gas block is dialed down as well? Or am I just going to have to mess around with different combos of buffer weights, recoil spring rates, and gas block settings?
For the sake of simplicity - assume a variety of Hornady or some other similar big brand factory ammo that's probably loaded to work with a variety of guns, not handloads that are only optimized to barely run 100% in one particular rifle.

There's no real formula for it because your component choices, the ammunition, and even something like your stance can affect how flat it shoots.

To figure out what gas block setting to start off with, contact your barrel manufacturer to figure out what buffer weight they expect to be used for their gas port size. Then adjust the gas block to restrict the amount of gas flow if your weight selection differs.

For example if they say designed for factory ammo with H2 buffer and you want to use a H1 buffer. That's about 20% lower mass, so start off by closing the gas port via AGB by 20%. If your AGB is 20 clicks from 0% (closed) to 100% (full open), then each click is worth 5%. So that's a 4 click adjustment before ever heading out to the range.

After that you need to figure out if your component selection along with your shooting stance is making you have muzzle rise (common) or muzzle dip (less common) by testing it. Record yourself while shooting with a camera app in slow motion 240fps to see at where during the action cycle the muzzle rise or dip is coming from.

 

[Slash]

Not necessarily. You can replace one or all of your weights with delrin or something. You can empty it completely. I have quite a few rifles that just have a delrin disk that sits in the end of the spring rather than an actual buffer. Weighs like .2oz.

One role of the buffer is to limit rearward travel of the BCG. The plug/bumper is there to cushion the blow when the buffer bottoms out in the receiver extension.

If your delrin disk is shorter than a buffer you are setting yourself up for problems. I’ve seen both sheared carrier keys and destroyed lower receivers because folks tried to use a buffer that was too short for their configuration.

 

[TonyTheTiger]

One role of the buffer is to limit rearward travel of the BCG. The plug/bumper is there to cushion the blow when the buffer bottoms out in the receiver extension.

Nope, I've got a limiting spacer in the bottom of the buffer tube.
Also have a bunch of rifles with these guys.

ULW Carbine Buffer System for AR15-223 | Taccom3g

Taccom 223 carbine length recoil system let's you lighten up your recoil system for a tuned, flat shooting competition gun. We STRONGLY recommend utilizing both adj gas and lightweight bolt with this system.

taccom3g.com

A little more elegant than cutting up and measuring delrin pieces.

 

[MontanaMan]

You're just canceling each other out and missing the entire point of each component.

This.

To make use of light(er) components, you have to limit gas.

MM

 

[Slash]

Nope, I've got a limiting spacer in the bottom of the buffer tube.

That wasn’t clear from the original post. I’d hate to see someone tear up their gun based on a vague/incomplete post.

 

[TonyTheTiger]

That wasn’t clear from the original post. I’d hate to see if someone tear up their gun based on a vague/incomplete post.

Good catch. My posts always make sense when I'm picturing the subject in my head, but aren't always so clear when I read them later.