View Full Version : Why Is The Carbine Buffer Only 3 oz?
With the Carbine Buffers we have-
Construction and Approximate Weights of Carbine Buffers
Standard Carbine- 3.0 oz. Three Steel Weights
H Buffer- 3.8 oz. One Tungsten and Two Steel Weights,
H2 Buffer- 4.6 oz. Two Tungsten and One Steel Weights
H3 Buffer- 5.5 oz. Three Tungsten Weights
Compared to the Rifle Buffer-
Rifle Buffer- 5 oz. Five Steel Weights and One Steel Spacer
If the Rifle Buffer weighed about 5 oz, how did they end up with a Carbine Buffer weighing only 3 oz? Why didn't they start off with a weight approximating the 5.0 oz of the Rifle Buffer? Is it because they didn't think to use tungsten?
IraqVet1982
09-11-15, 17:21
RDT&E. That's why...
Google DoD Acquisition process. I'm assuming the warfighter requirement was for a lighter rifle, why add 5oz if it functions with 3oz.
The rifle buffer is 5.15oz and contains 5 steel weights and a double long aluminum spacer.
IMO, the designers screwed up when they went overboard shortening the receiver extension tube, leaving room for only 3 weights and a shortened action spring.
Perhaps they didn't appreciate the benefits of a properly weighted buffer.
The A5 length with 4 weights and a rifle action spring is what the CAR system should have been in the first place.
Well, given that the Government Profile barrel was chosen (skinny where it should be thick, thick where it should be thin), I am surprised they even put in a buffer at all.
The rifle buffer is 5.15oz and contains 5 steel weights and a double long aluminum spacer.
IMO, the designers screwed up when they went overboard shortening the receiver extension tube, leaving room for only 3 weights and a shortened action spring.
Perhaps they didn't appreciate the benefits of a properly weighted buffer.
The A5 length with 4 weights and a rifle action spring is what the CAR system should have been in the first place.
I've always wondered why they didn't do so from the start.
Were the first M4s sold to the .mil supplied with carbine weight buffers? Or is the carbine buffer a legacy from the CAR/CAR clones?
My wild guess is that it works fine in properly gassed guns. KAC MOD 1 and MOD 2's seem to run alright, I guess.
Over the years, ammo grew "hotter", as M855 has more "dwell time" in the barrel than M193, and functions at similar pressure, the effect is that more gas is used in the cycling with M855. Now we have Alpha 1, and so on...
Then take into account all the people wanting to run Tula, and the "We'll just hog out the gas port and it will run with anything!" that many civilian companies went with.
What is the problem with the CAR buffer, CAR spring, and CAR buffer tube? Does it actually HAVE an issue? My answer is: No.
The gas port has an issue. All in the world that the buffer is for, is to counter-act the rebound of the carrier, and a CAR buffer will do this, quite nicely. The gas port should be sized correctly so that only the excess gas required for adverse conditions is pushed into the system. Once this is done, you can run the weapon, reliably, with a CAR buffer, or if improperly done, poorly with an H3. The gas port is the devil in the details, here.
My wild guess is that it works fine in properly gassed guns...
Were AR carbines ever properly ported to run with a carbine buffer?
My guess would be they made the receiver extension the length that it is so that when the stock was extended, it was the same length of pull as the rifle stock. This meant they could only fit 3 of the steel weights they already had on hand in the buffer. It functioned okay so there was no need to mess with it.
The 607 wasn't super reliable, probably partly due to the light weight buffer, and they introduced the XM177 and XM177E1. These were also not super reliable, probably partly due to the light weight buffer, and they introduced the XM177E2.
I wouldn't assume that the carbine buffer should be the same weight as a rifle buffer. Both because the gas port length and barrel length are different and because the recoil spring is different.
I've got a leftover RRA 5.4 oz buffer from my 9mm build that's running great in my BCM 14.5" midlength. As stated above, it's all about matching the buffer to the gas port. But I prefer the feel of a heavy buffer.
wildcard600
09-18-15, 17:23
My wild guess is that it works fine in properly gassed guns. KAC MOD 1 and MOD 2's seem to run alright, I guess.
Over the years, ammo grew "hotter", as M855 has more "dwell time" in the barrel than M193, and functions at similar pressure, the effect is that more gas is used in the cycling with M855. Now we have Alpha 1, and so on...
Then take into account all the people wanting to run Tula, and the "We'll just hog out the gas port and it will run with anything!" that many civilian companies went with.
What is the problem with the CAR buffer, CAR spring, and CAR buffer tube? Does it actually HAVE an issue? My answer is: No.
The gas port has an issue. All in the world that the buffer is for, is to counter-act the rebound of the carrier, and a CAR buffer will do this, quite nicely. The gas port should be sized correctly so that only the excess gas required for adverse conditions is pushed into the system. Once this is done, you can run the weapon, reliably, with a CAR buffer, or if improperly done, poorly with an H3. The gas port is the devil in the details, here.
All my BCM's run fine with carbine buffers with everything from tula to expensive defense ammo. I constantly see on the internet that i "need" an H buffer "at least" but many thousands of rounds later the guns just keep chugging along with that wimpy carbine buffer. Guess me amd my guns are to stupid to know that they should be unreliable.
About, 25 years ago, I asked some of the decision makers about this, the same thing. They knew that the carbine uppers could run with a wider span with a rifle action system on the lower compared to the carbine type system on the lower. It wasn't a secret then more than it is now. The rifle like action system worked better overall in function. It is a function of timing of events.
When asked specifically about the spring, RE length selection, and buffer mass, some interesting things came up.
The buffer mass was pushed as the most viable option at that time. I get conflicting reports of suitable tungsten weight inserts during those times being available for small or large production. Anyways, steel was accepted at the time knowing that is has the lower span of function when compared to a heavier one that may not have the ability to supply as components.
The RE length was meant to fit an AOL requirement that some wanted. I do not know where that came from, but it was a requirement at some time. On the base gun, the rifles ran worse for the requirement with less barrel length than less RE length. It was an consensus that to have more barrel length and less RE length. I do not know if this happened before or after the choice of tungsten weights was eliminated?
As for the spring? It was a modified rifle spring intended to work within the shorter RE dimensions. That functioned well enough, but less than ideal.
This was all done knowing that the rifle like action system performed better. They ended with a functional system, but with the addition of issues. I really think that the 3 ounce carbine action is a mistake for most. Even with proper porting, a 3 ounce buffer may have a lower range or span on function when considering the alternatives we have now.
Some AR's have longer gas systems to help address some base timing of events issues. A better way may or may not include that with a rifle like action system. The idea of the commercial A5, minus the internal spring, has been around since before my inital question a quarter century ago. Many different versions have been around in at least limited circulation from before my time.
I can not see in any way that the properly gassed 3 ounce carbine buffer action system can have any more of a range in function than a properly gassed version of the A5H2 system.
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