One thing that I always found strange about the AR is the component known as buffer.
AK, czech Vz., FAL, M14, SCAR and other popular designs do not have such thing, be them rotatory or tilting bolt. But well, all those guns have a piston, while the the AR has a DI system.
I thought I was on something, but then I checked other (and older) guns who were also DI, like the french MAS-49, and it didn’t have a buffer, just the usual recoil spring. But I know the DI of the MAS-49 is a bit diffeerent be less sensitive to fouling and also the gun has a tilt-locking bolt.
So, what makes the buffer necessary for the AR? The bolt carrier design, or the way the DI of the AR was designed? Combination of both maybe?
Can the buffer be considered a design weakness since it doesn’t allow a foldable stock and it’s another part to make the gun unecessarialy more complex? And I’ve also seen that buffer can cause bolt bouncing.
Here’s my simplistic stab at explaining the Buffer…
It is my understanding that the Buffer is necessary because of the designed size of the gun. The BCG could not be made heavy enough without making the entire gun larger. If a BCG could be made to weigh as much as both the BCG and the Buffer together, then you wouldn’t need the Buffer.
The added weight of the Buffer is critical to control the timing of the rifle. The Buffer delays the rotation of the Bolt. More weight, more delay. The Buffer is used a lot to compensate for improper Gas Port diameters. Too much gas needs more delay, so a heavier Buffer is used.
Delaying the Bolt’s rotation is to allow gas pressure to subside in the barrel (and chamber) to reduce stress on the Bolt’s lugs as it rotates and to allow cartridge to “shrink” to enable its proper extraction.
I’m curious if “my” understanding of the Buffer is correct, so we both might get schooled…
I do not know the technical ins/outs, but I’d suggest you consider this.
The AR15 platform has been around now for a very long time and has proven itself on the battlefield and at the most elite levels of competitive shooting.
I’m not sure where you got the idea that the buffer system is somehow a design flaw, but I think if you consider the success of the AR15 platform and its wide range of use today you will perhaps reconsider your idea that it is a design flaw.
A foldable stock is convenient, the buffer doesn’t allow that, so it’s already an issue even if a small one (or big for those inside a vehicle).
I don’t see how the buffer contributes to the “wide range of use”. Does the AR do something better that the, for example, the SCAR or SIG550 because of the buffer?
And the ROF of the AR in full auto is higher than the considered optimal 600-650 rounds per minute, specially when in short gas port of the M4, that easily gets to 900RPM even with the buffer to smooth things a bit.
Use of the buffer isn’t a design flaw, or a weakness. It’s a trade off. Remember, TANSTAAFL- There Are No Such Things As A Free Lunch.
While it prevents the use of a folding stock, it offers some important advantages. The M4 isn’t as short as it would be with a folding stock, yet it’s more accurate with the stock collapsed than it would be with it folded.
The buffer is more than added mass. It also acts as a shock absorber. The buffer also has the happy side effect of letting designers change buffers to tune the performance of the AR. Buffers help eliminate bolt bounce.
Having the action spring and buffer directly behind the BCG means all of the reciprocating mass moves directly inline with the bore and none of it tilts. And a line can be drawn down the bore directly to where the butt rests on the shoulder of the shooter. It’s also the line the recoil follows. All of this keeps muzzle rise to a minimum.
When any reciprocating mass is located above the bore, it adds to muzzle lift, as does having the bore above the shoulder of the shooter.
The downside is the face of the AR shooter is higher above the bore and is more exposed when shooting from cover.
It’s a fallacy to think the AR doesn’t have a piston. It does. The bolt acts as a piston and the carrier as the cylinder. What’s missing is the piston rod. One thing the buffer makes up for is the missing mass of the piston rod.
Also, placing the reciprocating mass to the rear of the rifle reduces the leverage it would have if placed out towards the muzzle. It’s close to the center of mass of the shooter, where any disturbance of the muzzle is damped by the body and improves balance. In many ways, the design of the AR is brilliant. It’s very simple, yet it’s refined. It uses controlled tolerances so it can be easily assembled, maintained, repaired and modified once the parts are made, yet it easy to manufacture. It’s ergonomics not only allow ease of handling, but offers every advantage to controlling recoil. All of these traits make it inherently accurate. There is little that needs to be done to get an AR to shoot well. No other rifle design brings all of these elements together in a single package. Stoner got the basic design right
I think the whole design including the buffer is a great design. You will start to love it even more when you think of the BCG as a piston. Kinda reminds me of a locomotive:blink: The way the bolt opens and and cycles just seems so much smoother and softer than a short stroke that just violently whacks the BCG. (i dunno: somehow thats how i visualize it)
The buffer is necessary as a medium for the bolt carrier to contact when the action cycles. This two piece buffer/carrier design allows the upper to separate from the lower and not have any springs to disassemble during this process. The fact that it adds a ‘tunable’ aspect to the rifle is more than welcome.
There have been foldable stocks for ARs. They never caught on because the collapsible one serves it’s purpose. The action spring system is simple and robust.
This thread isn’t “explain how it works,” it’s “justify this part of the basic design.”
I thought this was the ar tech section. I joined m4carbine because it was a step above the rest. You just turned it into TOS. Mods, why no time out for this gentleman?
tog
Don’t get me wrong, man. I was actually curious about this matter and the thread has been great so far.
So, back to the topic, why, even with the buffer, the RPM of the AR is relatively high? The BCG is too light or the DI is hard to regulate since the gas contact is direct instead of havinga piston to filter and regulate?
I’m not with Markm, but I defend his point. This isn’t a needed topic, and if you read a few stickies you’ll understand why you need a buffer in a rifle of this design.
That said, the OP doesn’t seem to be much of a douchebag to me, and asked the question in a respectful ‘‘learn me up’’ manner, and I’d be happy to answer him.
Well, I feel entitled to knowledge, I admit. I mean, the internet is very addictive for those who like to know about many things like myself and I’m aware this forum here is one of the best place in the whole internet to get info on anything AR.
And I know that, for many americans, everything about the AR seems to be “the standard”, but it’s quite clear that the buffer is a very unique aspect, considering that all other major rifles, be it battle or assault, lack the buffer, even the ones who are DI like the AR.
So are you saying it doesn’t work well? After reading the advantages given above how would you remove the buffer system, what would you replace it with and what would the AR lose in the process? A few things to consider are overall weight, strength of the receivers, size of the receivers and balance of the weapon. The whole design of the AR is brilliant and it’s difficult to remove one integrated system without adversely affecting other systems. The buffer is an important part of the almost unique in line design of the barrel, entire BCG, receiver and recoil spring/buffer - which give you increased accuracy and less muzzle rise.
Also the military has been using this design much longer than the older traditional designs it replaced, about 50 years vs. maybe half that for the Garand and some bolt actions. Something must be right.
