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Standard vs Carbine Length Buffers


Graham Smith

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As I try and learn more about how AR-15's work, I'm finding that there is a clear relationship between things like barrel length, gas tube length, bolt carrier weight, buffer weight, and buffer springs. While I understand much of this and am learning more every day, one thing I almost never see mentioned has to do with the apparent interchangeability between standard and carbine length buffer tubes to accommodate different stocks.

I would think that putting a carbine length buffer tube assembly on an AR with a rifle length gas system would affect the way it works (and vice versa). But I'm not seeing any mention of this in what I have read so far. My guess is that it must not make much difference but I'm not sure why.

On several occasions, I've seen it mentioned that a standard length buffer results in a milder recoil, presumably because it absorbs more of the recoil. But it's also possible that guns with A1/A2 length stocks are more likely to have rifle length gas systems which is what's really making the difference.

Bottom line is this: Will changing from a standard length buffer tube to a carbine length tube have any noticeable effect on the way the gun shoots?

Very confusing.

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Carbine buffers cannot be used in rifle length tubes. Notice there is a difference between gas systems and stocks. They are not conducive to one another. Carbine stocks use a carbine buffer tube which takes a carbine length buffer. Rifle stocks use a rifle buffer tube and a rifle length buffer. But yes,buffers vary the recoil impulse and it is different for different gas system lengths.

Attached is a good reference that shows the composition of the different buffers.

post-8688-126719917726_thumb.jpg

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It is possible to use a carbine buffer in a rifle stock (rifle length tube). BUT, to do this you need to fabricate a spacer to go in the back of the rifle tube to take up the difference in length between the carbine tube and the rifle length tube. This will stop the carrier from going too far into the tube and damaging the gas key or the lower.

I think MSTN will sell you one.

I turned one out of a block of nylon.

If you want a lighter buffer though, probably better to mess with the weights in the buffer. (a search will find links to replacing those weights in the buffer with other material, etc

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It is possible to use a carbine buffer in a rifle stock (rifle length tube).

I think that I'm still not getting my question right.

Assume you have an AR-15 with a 18" - 24" barrel, a rifle length gas system and an A2 stock. If you remove the stock, buffer tube, spring, and buffer, and replace them with a carbine length buffer tube, spring, buffer, and collapsible stock, what effect will that have on the action?

Edited by Graham Smith
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It is possible to use a carbine buffer in a rifle stock (rifle length tube).

I think that I'm still not getting my question right.

Assume you have an AR-15 with a 18" - 24" barrel, a rifle length gas system and an A2 stock. If you remove the stock, buffer tube, spring, and buffer, and replace them with a carbine length buffer tube, spring, buffer, and collapsible stock, what effect will that have on the action?

In other words, a rifle upper on a lower with a carbine telescoping stock. If that's what you're talking about, I've done it and it works fine.

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It will work just fine. Add an adjustable gas block to equation and you get a lot less muzzle flip.

I know that this is done all the time and that it works, but I'm not sure if there is a difference and what that difference might be. So, when you say it "will work just fine", do you mean no difference at all or a little difference? If it's just a little difference, what kind? More recoil or cycling problems? It's the cycling problems and the wear that goes with them that concerns me somewhat.

Regarding the adjustable gas block, I assume that is to allow for the reduction of the gas as compared to a standard gas block to "tune" the cycling?

Assuming the weights of the buffers are the same.....you will not see a change in recoil of the gun.

Good point. Now that I think about it, a standard rifle buffer and a standard carbine buffer are different size but are the same weight and use the same spring. <sound of hand slapping forehead>

-------------------

Sidebar: I realize that I'm probably getting into the minutia with questions like this, but that's one of the side effects of getting a lot of information. You start to wonder what the effects are of changing things. There's also the issue of relative differences. For example, if you say that 80db is twice as loud as 70db, the implication is that if 70db is loud then 80db must be deafening. But it's not really because "twice as loud" only refers to the mathematical relationship between the two, not the perceived difference.

So, while I know that there must be some differences in swapping between an A2 and carbine stock, I guessing that they are rather small. I just wanted to know what differences there might be to determine if there is a enlightened (good word that) way to make such a swap.

Edited by Graham Smith
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Carbine buffer springs are shorter than rifle springs, that's why the buffer is smaller. Magpuls carbine stocks lock down pretty good, but really for competition and general shooting, the rifle stock like a VLTOR is probably better. Collapsible stocks are great for armor and door knockers, but they tend to flop unless you can lock them down or tape them. It's fun!!!

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I switched from an ACE Skeleton stock to a LMT SOPMOD collapsible and the "twang" you sometimes hear and feel in the A2 stock assembly (or skeleton in my case) is no longer is present. I didn't feel any difference after the switch but I like the SOPMOD as it's a bit longer than the skeleton and provides a better cheek weld. I guess I didn't help much either, I did keep the weights of the two buffers very close to the same :blink: And I run a RRA carrier with 3 ounces in the back.

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Assuming the weights of the buffers are the same.....you will not see a change in recoil of the gun.

The lightened JP rifle length buffer is 3oz.

Its basically a rifle buffer with the steel weights replaced with aluminum.

what I did was buy a 1/2" aluminum rod from the home Dept and cut and sand it to match one of the steel weights , = it has worked for a year with out any signs of damage.

my split times are slow, but just the same I can not much tell the diffrence with a shop lighting job on my Carrier.

Caspina-Guy's responce was the best about why not to

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Is there any benefit to running a lightened buffer with a stock carrier?

I've tried it and can't say enough to notice. It did have a few failures to go into battery wit the lighter buffer. Since going back to the standard rifle buffer...many thousand rounds later and no more failures to go into battery.

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Carbine buffer springs are shorter than rifle springs, that's why the buffer is smaller...

Is that true?? I thought there was only one length buffer spring for both rifle and carbine buffer systems... :huh:

Rifle buffers and tubes are longer of course, but the spring sits on the ridge on the rifle buffer, which matches up to where the head would be on the shorter length carbine buffer in a carbine tube.

Is there any benefit to running a lightened buffer with a stock carrier?

I've tried it and can't say enough to notice. It did have a few failures to go into battery wit the lighter buffer. Since going back to the standard rifle buffer...many thousand rounds later and no more failures to go into battery.

Regarding buffers, I've also heard that (with a rifle-gas system) even with a lightened bolt carrier, lightened buffers are not as reliable as standard weight rifle buffers...

Edited by Xfactor
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I thought there was only one length buffer spring for both rifle and carbine buffer systems...

I'm rather confused about that myself. I've seen springs listed separately for standard and carbine and others listed as being for either one.

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In terms of coil type springs....there are two lengths of recoil spring to fit the buffer tube. Of course the carbine buffer tube and buffer are shorter than rifle length so the spring is shorter and vice versa. Flat wire springs are the same length as they stack differently in the tube and different length springs are not necessary.

And yes.....reliability can be degraded when the operating system is lightened.

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In terms of coil type springs....there are two lengths of recoil spring to fit the buffer tube. Of course the carbine buffer tube and buffer are shorter than rifle length so the spring is shorter and vice versa. Flat wire springs are the same length as they stack differently in the tube and different length springs are not necessary.

And yes.....reliability can be degraded when the operating system is lightened.

Makes sense about the flat springs... I was looking at a Tubbs flat spring, and an ISMI (Which I believe is also flat) and didn't see any length options.

The great thing about an AR is that there are so many options and variations to choose from.

The worst thing about an AR is that there are so many options and variations to choose from.

+1 :lol:

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The great thing about an AR is that there are so many options and variations to choose from.

The worst thing about an AR is that there are so many options and variations to choose from.

More true words were never spoken.

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I just today switched an A1 stock to a Magpul ACS.

This is on a 16" mid-length gas and this is my first time firing anything with an adjustable carbine stock.

All new parts supplied with the ACS "KIT" and I assume the buffer is a standard carbine weight.

The recoil impulse is definitely different!

This gun bounces all over and split times were terrible.

I actually got a mild headache after shooting 40 rounds.

The recoil is much sharper and seems to transfer right to the stock and to my cheek/head bone.

Honestly I think it was a huge waste of money.

I shot a dozen with NO lube on the buffer/spring and then greased like I have done on every AR since I shot highpower to get rid of the "sproing" noise.

Now, after reading this, can I save my experiment by replacing the standard buffer with an H1-H3?

Is a lubed carbine buffer not the thing to do?

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Time for adjustable gas block, i'd say... I'm running empty rifle buffer and rifle length buffer spring w/20" barrel w/adjustable gas system. Those two things definitely helped my shooting a lot. a VERY noticeable difference in muzzle flip and the sights came back on target much faster. Some guys are running similar setups as mine, with a spacer in buffer tube (rifle length buffer tube), with carbine spring and empty carbine buffer. When it comes to repricocating (i really cannot spell that word) mass and splits times, less weight is better... But that calls for adjustable gas system.

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I've played with a lot of different combinations. (3-gun competition applications, semi-auto only)

Aluminum Bolt Carrier

Tit bolt Carrier

lightened steel carriers

Empty rifle length buffers

removing 1 or 2 weights from buffers

Carbine buffer w/ spacer

The issue here is "reciprocating mass" of the BCG & Buffer. Just like some people want lightened slides on their pistol, some people like lightened BCG's & Buffers on their rifle. Does it make it different? YES. Does is make it better? Not sure.... There are a lot of factors that are effecting what YOU see down your sights/scope. Compensators, gun overall weight, ammo, how you hold your gun. A gun that recoils great for one person my feel strange to another. Find what feels and works good for you.

Get your BCG & buffer too light and you're flirting with function problems as well as sharp recoil impulse. Too heavy and your gun will, what I like to call, feel LUMPY. Kind of slow recoiling.

I've come full circle, from very light to my current set up, full weight everything. I tend to think that powder/bullet/gas port size combinations have more effect on recoil than most of us realize. I believe that you can take any gun and find a load (reloading)that feels the way you want it to. In reality, an adjustable gas block does nothing more than give you an easy way to compensate for variences in gas pressure/volume.

Edited by BPiatt
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