Standard vs Carbine Length Buffers

[aessu]

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 like the sharp recoil impulse. Sharp, quick cycling gets me the fastest split times. But there is definately need for adjustable gas block when lightening the moving parts - the rifle would be very hard to shoot without it and would probably also cause a lot of malfunctions. I should be able to finish my own lightened carrier next week and tune the adjustable gas system for it (tuned it for this weekends club match w/just empty buffer). The rifle is probably going to need more maintenance with lighter moving parts, but that's something I'm willing to do for much faster splits.

[Xfactor]

...I've come full circle, from very light to my current set up, full weight everything...

Hi Bruce,

Do you find that your splits are equally fast with a full-weight bolt carrier and rifle buffer, or is it just that you're willing to sacrifice a little cyclic speed for a smoother feel?

[sierra77mk]

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?

My further experimentation with collapsible stocks and carbine buffers.

I installed a RRA 9mm buffer. Weight = 5.4-5.5 oz.

This is .3-.4oz heavier than a rifle buffer as per 00bullitt's posted image.

Gun shoots MUCH better now. Feels what I expect an AR to feel like. I just can't see how that light buffer slamming back so fast into the buffer tube is a good thing. I understand the theory and physics of lighter moving parts... but in the real world the light buffer bounced me all over and gave me a headache.

I guess it depends on the kind of shooting you do. I want a carbine set up primarily for mid-range accuracy [100-300 yds] not run and gun arms length shots. That's not usually the type of matches I shoot.

As a side note, and I cannot say whether the heavier buffer had anything to do with it, however I shot one of the best 100 yd groups today with 68 hornady's. I was sighting in a new Burris XTR-14 so it was probably the scope. But that heavy buffer smoothed out the recoil impulse tremendously.

[aessu]

I personally prefer the lighter moving parts, but you need adjustable gas system to have any advantage of them! I have taken all the weights out of the buffer tube and run a lightened carrier. But there's also one thing. How you hold your rifle. With light weight internals, if you just hold it tight, it will be super fast to shoot.

Edited April 11, 2010 by aessu

[gotm4]

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.

Actually you can use a CAR length buffer and spring in a rifle receiver extension. You will need something to take up the difference in space. The RRA 9mm spacer does just this thing. RRA part # 9MM0073 $8.00

http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=244

FWIW a standard CAR buffer is the same 3.0oz as a JP/LMOS rifle length buffer, but a CAR buffer spring is shorter and stiffer than a rifle length buffer spring. Thus the difference in feel.

CAR length buffers work well with any barrel length. The Canadians use them in their C7A2 (20" barrel) with a M4 stock (4 position), They use H2 buffers.

Edited April 11, 2010 by gotm4

[Graham Smith]

I'm back on this topic again but with the emphasis changed to the buffer weight. I've switched from the A2 stock to a carbine stock, spring and buffer. It works well but the recoil is somewhat "sharper" than it was with the A2 stock.

So, what I'm trying to understand now is the relationship between the buffer weight and the rest of the action. Given that I have a rifle length gas system, I would think that a standard carbine buffer would be OK, but from what I can find it seems that a slight increase in weight to a H1 buffer might soften it a bit without any performance problems.

[sierra77mk]

I'm back on this topic again but with the emphasis changed to the buffer weight. I've switched from the A2 stock to a carbine stock, spring and buffer. It works well but the recoil is somewhat "sharper" than it was with the A2 stock.

So, what I'm trying to understand now is the relationship between the buffer weight and the rest of the action. Given that I have a rifle length gas system, I would think that a standard carbine buffer would be OK, but from what I can find it seems that a slight increase in weight to a H1 buffer might soften it a bit without any performance problems.

Yes that's what I found. I got the 9mm buffer from ADCO because my research and others I asked said it would work. I figured my rifle had a 5.1 oz standard rifle buffer with a midlength gas system. I switched to a 5.5oz 9mm buffer so a little extra weight and the greater pressure of the mid-length would offset and would run fine. So far it works with mild 55gr loads and 62 surplus and 68-9 handloads.

Your rifle length gas would probably run fine with an H2 buffer judging by weights in 00bullitt's chart.

This is a good reference thread:

http://m4carbine.net/showthread.php?t=6827

and this too:

http://www.m4carbine.net/showthread.php?t=873

[AKJD]

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...

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...

Rifle Action Springs are 11 3/4 to 13 1/2 inches. Carbine Action Springs are 10 to 11 1/4.

[Graham Smith]

Rifle Action Springs are 11 3/4 to 13 1/2 inches. Carbine Action Springs are 10 to 11 1/4.

Except that there are some springs that are listed as fitting either a standard or carbine length stock. Go figure.

[Graham Smith]

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.

Thanks Bruce. The variables in all of this make tuning pistols seem like a walk in the park.

I started with a an 18" 1:8 barrel with full length gas system and a standard A2 stock. I have a relatively long LOP so the A2 stock was OK sometimes and a bit too long others. I switched over to a Vltor EMOD stock which is a bit longer than an A2 at full extension but can be reduced if needed. Of course, in doing so I had to switch from a rifle spring and buffer to a carbine and I can definitely feel the difference.

So, in my continued quest for knowledge, which is a hobby unto itself, I started trying to understand about the relationship of buffer weight to everything else. What strikes me as odd is that a standard rifle buffer is around 5oz while a standard carbine buffer is only around 3oz. So switching from an A2 stock to a carbine stock, you essentially drop 2oz off the buffer. Wouldn't it make sense to go with an H or H2 buffer to change the weight back closer to what it was before?

[jwfuhrman]

I have 3 AR's. 1 is a standard A2 that I have from my NRA Service Rifle match days, the other 2 are custom built, both are BCM guns that I pieced together on S&W M&P15 lowers.

My SBR has a 11.5in BCM barrel, BCM BCG and Magpul ACS. I run a H2 buffer in there. Because of the short barrel, the recoil was crazy with a standard carbine buffer. The H2 slowed the cycle rate down far enough to help smooth out the recoil.

My other AR is a REECE build, again, all BCM on M&P15 lower, 16in SS410 Mid-length gas system. Except Im running a A2 stock with a standard A2 buffer. This gun is my Mid-range rifle(100-600yrds) with a 3-9x40 Burris scope. I prefer to run fixed stocks on my scoped guns.

Here are a couple things to consider.

If you want to use a collapsable stock, try to stay away from stocks like a standard M4, the CTR, MOE, or any stock like that. They are tooooooo light for what you want to use the gun for. Go with a SOPMOD, ACS, or UBR. The extra weight, plus a heavier carbine buffer will help big time. General rule of thumb is to use a buffer that is just light enough to keep your gun running reliably but heavy enough to help control recoil and cycle rate.

When I have the cash, Im going to be getting a UBR and H2 buffer for my Reece Rifle and probably a UBR for my SBR as well. They are the best combination of weight, fixed cheek weld, adjustable shoulder length stock on the market.

Ive learned most of this from m4carbine.net (not sure if Im aloud to post that or not, just wanted to for reference to where Ive learned the most about the AR/M4 world).

Hope I helped!

Edited April 23, 2010 by Jon Fuhrman

[swhiteh3]

Dragging this thread up from the dead.

I'm building a mid-range precision match rifle in 5.56. This is mainly a precision rifle - 90% of my shots will be out past 100yds, and many out to 600yds, as a "Secondary" shooter in a sniper team. (They also throw in some short-distance / CQB / Squad Protection / 3-gun type stuff).

The rifle will be built with a 18" barrel (match limit), mid-length gas system, adjustable gas block, and rifle length buffer. I'd like to run the XLR Tactical Buttstock, and they recommend the carbine length buffer tube for that on AR15 rifles.

Since this is mostly a precision rifle where a few hundredths of shot split time are not important, but being able to take a precise shot and watch through the scope as the shot is fired is CRITICAL, would a heavier buffer typically be desired?

If I have to move to the carbine length buffer tube, which buffer spring / tube / buffer weight is most likely to be correct? Should I start with a typical carbine tube / carbine spring / "H" buffer?

[TonytheTiger]

I would think going with a rifle length gas system would have a more noticeable effect on your ability to spot hits than buffer weight will. And you can always take buffer weights out one at a time and see what feels best for you.

[doogiehowitzer]

I agree with Tony if possible I would use a rifle length gas port. Either way if you have an adjustable gas block I would think an H buffer with a standard spring would be fine.

[Novock]

great topic. I am looking at putting on a Magpul PRS stock on my 18" competition rifle which currently has a carbine buffer system in it. was curious how this buffer change would affect performance. Think i have my answers.

[bagdrag]

I have a XLR Tactical Buttstock on one of my rifles and as far as I know it uses a pistol buffer tube. I don't have a pistol so not sure, but just assuming that they are using a standard non-proprietary tube of some sort. Either way it doesn't/can't use a rifle length or carbine length buffer tube due to the mounting attachment for the stock. It does however use a carbine buffer (weights removed and replaced with delrin pieces) and spring. My rifle has an 18" barrel with a rifle length gas system and adjustable gas block.

Not sure yet if I like the lighter (weights-free) buffer. Probably matters much less than the other parts of the configuration like the rifle length gas, adjustable gas block, LMOS BCG, and comp.

[Rangerdug]

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?

Yes there will a change in recoil impulse. It is simple Law of physics. Every action has an equal reaction. Every action in AR has a counter action for it to work correctly. As you stated before barrel lengths and gas systems effect the BCG. The shorter the gas system the faster the bolt carrier is moving rearward. In the case of the M-4 not only was the barrel shorter but also the buffer tube. So how do you control the faster recoil impulse with a short gas system and maintain controllability. You have to shorten the buffer to compliment the shorter buffer spring.

With a longer barrel 18-24 inches rifle length gas system the gases have longer length travel. The recoil impulse of BGG is slower. Now, since you know have a longer buffer tube and a longer spring(more coils) you need more mass (i.e. The rifle buffer to return the BCG back into battery).

So to answer your question. Can you run a M-4 buffer on an 18inch barrel? Yes. Can it make your gun less efficient? Yes, but probably not that you will notice. I would go to the heavier carbine buffer(H2 or H3).The exceptions must be noted. If the gas system is carbine length, all day. Also if you have adjustable gas block. Also the JP silent recoil system. You can change springs on it to tune to your gun. Honestly, the only way to know is try it.

Sent from my iPhone using Tapatalk

[kurtm]

Whether it is a "carbine" length tube with carbine buffer, OR a rifle length tube with a rifle length buffer, the amount of bolt travel is IDENTICAL!!! therefore spring length between the two means NOTHING. The bolt still travels the same distance under an identical amount of sprung distance! The only difference is that a non heavy carbine buff is lighter than a rifle length buffer. A regular carbine buffer is equal to a J.P. light RIFLE buffer.

[Alaskapopo]

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.

Generally you can switch back and forth unless you get a combo where say you had a carbine upper with a small gas port and say some weak ammo and then stuck a lower with a rifle buffer on it. Then you may get failures to lock back or short cycling but this is rare.

Pat

[Tim187]

On 2/26/2010 at 10:01 AM, Graham Smith said:

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?

It could possibly short stroke if that's done

 

[Tim187]

I built an 18in 223 wylde with rifle length gas system and carbine buffer system and it's a short stroking mf 

[TonytheTiger]

2 hours ago, Tim187 said:

I built an 18in 223 wylde with rifle length gas system and carbine buffer system and it's a short stroking mf 

Then a longer heavier buffer will make it short stroke worse. You don't have a buffer problem, you probably have a gas block alignment problem.