That's awesome, thanks for the link:dance3:
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I think you are a bit too wrapped around the design of the AR-15 buffer and action spring system, to clearly see how the other systems work.
First, let's define what a recoil buffer is:
A component that reduces the velocity and/or cushions the impact of the recoiling parts of a firearm.
The AR system is just one take on a buffer system.
Like I said previously, other systems have buffers, they are just designed differently. In the AR, the buffer system is located in the receiver extension; it houses the buffer and action spring.
In other systems, the action sping is located in the upper itself, sometimes combined with a guide rod, and the buffer is mounted on the receiver end plate, or stock, and cushions the impact of the reciprocating bolt.
A few examples:
G3:
Showing different HK buffers:
http://img844.imageshack.us/img844/2...ilbuffers4.jpg
Fixed stock and action spring/action spring rod:
http://img545.imageshack.us/img545/142/g3f16.jpg
Collapsible stock, part of buffer visible above latch
http://img59.imageshack.us/img59/8158/813340.jpg
Cutaway view:
http://img571.imageshack.us/img571/6214/p1000231mn2.jpg
MG 3:
Buffer:
http://img37.imageshack.us/img37/5302/mgbufferniw.jpg
Recoil Spring:
http://img221.imageshack.us/img221/1074/newbatch009.jpg
Stock:
http://img685.imageshack.us/img685/8...buttstock3.jpg
Removal of stock and recoil spring:
http://img22.imageshack.us/img22/5482/mg31.png
Removal of buffer:
http://img600.imageshack.us/img600/6053/mg32.png
FN MAG:
Stock, number 6 is buffer:
http://img607.imageshack.us/img607/3605/fnmag1.png
Showing recoil spring and rod attached:
http://img854.imageshack.us/img854/7966/fnmag2.png
Recoil spring and rod removed:
http://img502.imageshack.us/img502/2930/fnmag3.png
Now, I have not handled a SCAR or ACR, but from what I can see from the pics you posted, the action spring assembly works as the buffering mechanism, and there is probably something on either the stock or on the action spring rod that cushions the impact (vertical bar on the SCAR rod, and white rubber knob on ACR rod I think).
Again, a buffering system is just that, a system; execution can vary from weapon design to weapon design.
Great post Arctic1. As was explained to me by someone we would all know at SHOT a few years ago, the design may be somewhat unique in regard to the tube but is in no way inferior. The only time issues arise on a practical level is when full concealment is desired.
There is an after-market buffer available. Anyways, the action spring is a buffer system, it just doesn't have anything to cushion the impact of the reciprocating parts.
What weapons have you worked with that don't have a buffer?
To be honest I can't think of a single weapon in the FDF arsenal that has a buffer. Sako/Valmet, PKM etc. don't have one.
There are aftermarket buffers for the AK, but they will cause problems. Depending on the design they may cause the bolt to short stroke and regardless of the design the have ability to break down. I broke an US made buffer only after few hundred rounds, and the best ones in few thousand (at least the ones I have shot). When they break the parts will drop into the fire control group and cause problems. They do alter the felt recoil and IMHO make the gun a bit nicer to shoot, but also IMHO they definately are not worth the hassle.
A good analogy for the firearm action spring and buffer is the spring and bump stop system used on automotive suspensions.
In the simple case of a leaf spring truck axle, there will be the leaf spring (action spring) and a bump stop (buffer).
The bump stop is most often a rubber on steel contact point, but can be steel on steel in the case of overload springs like used on a dump truck.
http://www.google.com/url?source=img...foqqmtTmdfDl2w
One other key defining feature is:
the action spring is active during the full action stroke,
while the buffer is active only during a short distance at the end of the recoil stroke.
The AK's bump stop is generally the rear trunion, steel on steel.
Other firearms use a very heavy spring, or an rubber/urethane bumper as the bump stop.
The original M1918 BAR has a heavy "buffer spring" surrounding the "actuator spring" (action spring) .
http://i14.photobucket.com/albums/a3...itor/BUTTS.jpg
http://www.armspost.com/blog/wp-cont...patent-bar.jpg