View Full Version : Buffer Tube 101?

02-16-2007, 8:59 AM
Can someone give me a crash course on buffer tubes?

I keep reading references to mil-spec, commercial, and what not. From what I've gathered so far there are two lengths -- A1/A2 length and carbine. Correct?



02-16-2007, 9:09 AM
The mil-spec myth is regarding to the outter diameter of buffer tubes, especially those tubes for collapsible buttstocks. A lot of commercial buffer tubes do not follow the mil-spec. They are (mostlikely) lager than mil-spec.

The combinations are pretty confusing now.

Magpul makes buttstocks for both mil-spec tubes and none-mil-spec ones.
Manufacturers like Vltor, LMT....make mil-spec buffer tubes.
Manufacturers like RRA makes none-mil-spec buffer tubes.

Do some research and you will get the ideas.:)

02-16-2007, 9:42 AM

if you are asking about fixed stock AR tubes, they are the same for the A1 & A2, the A2 comes with a spacer and longer screw. There is no difference in manufactured diameters for the fixed stock buffer tubes afaik~

02-16-2007, 9:44 AM
Mil-spec also technically refers to many other things such as surface finish, coatings etc etc...most buffers you come across are not quite mil spec.

This doesn't make them bad necessarily, just different.

02-16-2007, 9:58 AM
What about the AR10? Different tube (then the ar15)? Different buffer?

02-16-2007, 10:38 AM
The lengths are A1/A2 length, and carbine length.

As mltrading said, the outer diameters are different in some of the nonstandard ones. That's why lotsa folks stay away from RRA & bottom-feeder carbine stock assemblies, because those tubes reduce prospects of future changeouts of the actual stock itself.

Oh - BTW/FYI, A1 length buttstocks use a shorter stock screw than A2 length stocks. A2 length stocks use a spacer at the end of the buffer tube (real name: "receiver extension")...

02-16-2007, 1:34 PM
Anyway, for myself, I'd stick with true mil-spec stuff. The interchangeability is better than those are none-mil-spec.

If I have no choices but take none-mil-spec ones, I'd make sure to get whole set. For example, get whole set of RRA 6-pos M4 stock including buffer/tube/spring.

02-16-2007, 1:46 PM
So does my RRA 6 position stock use a non Mil-spec buffer/spring?

Technical Ted
02-16-2007, 2:01 PM
So does my RRA 6 position stock use a non Mil-spec buffer/spring?
Carbine springs and buffers are interchangeable.

FWIW (These are a couple of years old and I no longer own the RRA stock). Colt Military Spec on top, Commercial on bottom. Colt buttstock has a GG&G Sling Thing for a QD sling swivel installed:

Collapsed. The Commercial buttstock assembly is larger and longer than the mil-spec buttstock assembly. Also note that the reinforcement rib in front of the latch is curved on the Commercial buttstock.

Extended. The Commercial buttstock extends further.

Bare receiver extensions. Commercial receiver extension is longer and the rear is angled to match the angle of the buttstock.

Receiver extension cross section difference. The Commercial receiver extension has a larger diameter. Also observe the junctions where the buttstock rail meets the receiver extension: the Commercial stock has a concave junction, AKA fillet.

02-16-2007, 2:38 PM
thank you ted,

That information is incredibly useful. I was having a devil of a time figuring out the 'milspec' 'commercial' details when it came to stocks.

I'm building an OLL and was trying to figure out what to get.