Lower Receiver Schematic Drawing showing tube-buffer-spring assembly |
Self-loading rifles and pistols require
a recoil spring to cycle the action. The AR or military M16 is
lightweight, therefore it requires a buffer that provides extra
weight. The action energy is absorbed by the spring, so compression
is important in order for the stored energy to push the buffer,
carrier and bolt back in the forward position.
Plunger pin holds buffer in place |
At the rear
inside of the lower is a small plunger at the face of the buffer.
Depress the plunger and the buffer spring will push the buffer out of
the tube. Once the head of the buffer clears the plunger, grab the
plunger and pull it and the spring out of the tube. Sometimes it
takes some wiggling to get it past the hammer, which should be
cocked.
Springs for the rifle and the carbine
are the same diameter and made of steel alloy. The rifle springs have
41 to 43 coils, and the carbine springs have 37 to 39 coils.
If you have bought a used rifle or
carbine and find that a spring has been shortened by cutting off
coils, it should be replaced. If you find the spring has been
shortened, it will need a complete inspection because other parts may
have been altered, which is why the spring was shortened. You will
have to find the reason why the previous owner cut the spring.
Springs also shorten with use. When a
spring has gotten shorter than the recommended length, replace it.
The rifle spring should be more than 12-inches long and the carbine
spring should be more than 10-inches long. If they have shortened to
those lengths or shorter, replace the spring.
Rifle and carbine springs should never
be interchanged. In an 'emergency', one could get by by
'cannibalizing' parts from one firearm to another, but replace with
proper spring as soon as possible. The longest spring found has been
50 coils long; which made the rifle frequently short-stroke and
failed to eject. Counting coils is important when inspecting a newly
purchased used AR series rifle.
The photo below shows the difference
between a carbine buffer (top) and a rifle buffer (bottom). The
bottom buffer is what you would see in military issue rifles. So the
rule is: there is only one buffer that will work properly – six
inches in length.
Photo by Gun Digest |
For carbines, however, there are
several buffers available. The shorter carbine buffer lacks the
second spring shoulder found on the rifle buffer. Some carbine
buffers are made of plastic instead of machined aluminum; indeed, if
you have a lathe and the skill, you can make your own buffer as long
as the measurements and weight are correct. Plastic buffers are
filled with lead shot. I suggest you replace the plastic buffer with
the aluminum so there will be no function problems.
A proper buffer is made of turned
aluminum, 3-1/4 inches long, with a nail-like head (like in photo) and a
plastic tip, which military rifles have a nylon tip that wears
better.
If you shake the buffer you may hear and feel steel weights
inside banging back and forth.
Buffer cutaway showing weights |
If a carbine works properly with this
configured buffer, no need to replace it unless you prefer to
purchase a better quality buffer. If, however, you experience
occasional malfunctions that you cannot figure out its origin, such
as a failure to extract, and the extractor is bent or broken the rim
of a cartridge, replace the buffer with a heavier one, like what Colt
developed for military rifles. If you want to purchase something more
economical, replace buffer on carbines with H or H2 buffers. In
extreme cases, a carbine may require an H3 buffer.
Once again, never, ever, exchange
buffers between rifles and carbines. If you use a rifle buffer in a
carbine, the result, if you are lucky, will only be that the carrier
key screws shear off. If the carrier screws do not shear off, or do
so in a timely manner, the lower receiver will crack at the buffer
tube threads. Then you will have to purchase a new receiver, which is
more expensive that a proper buffer.
NoKick
offers custom reduced kick buffers for the AR-15 and AR-10, for fixed
and collapsible stocks. They are not cheap, the AR-10 Silent Captured
Spring buffer system costing $130 to $140.
The AR-15 9mm buffer is available in a
hydraulic model costing $125. The 9mm Silent Captured Spring system
costs $130. A hydraulic recoil buffer is available for the fixed
stock in AR-10 and AR-15 models. Buffers are available in stainless
and tungsten.
The following video is informative concerning AR buffers springs ...
The next video covers buffers ...
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