Colt Factory Original M16A2 Fixed Stock W Buffer Tube Rifle Buffer And Spring

About this product

This is a Colt factory-original M16A2 fixed stock kit, sold complete with the rifle-length buffer tube, rifle buffer, and action spring needed to install it on an AR-15 or M16-pattern lower. It's a parts kit rather than a complete firearm, aimed at builders and restorers who want genuine Colt/mil-spec components instead of aftermarket reproductions. The A2-style fixed stock has been standard on M16A2 and many AR-15 rifles for decades, and this kit gives you the full assembly rather than piecing it together from separate vendors.

What is this kit?

It's the rear furniture and internal buffer assembly for an AR-15/M16-pattern rifle: a non-adjustable A2-profile fixed buttstock, the rifle-length buffer tube it mounts on, a rifle-weight buffer, and the action spring that returns the bolt carrier forward after each shot. Together these parts replace or complete the rear half of a lower receiver build, and being factory Colt parts, they carry the fit and mil-spec dimensions original M16A2 rifles used.

What is it used for?

Builders use kits like this to complete a stripped lower into a rifle-length AR build, restore a rifle to original A2 configuration, or replace a damaged or non-mil-spec stock assembly with genuine parts. It's a common choice for retro AR builds meant to replicate a period-correct M16A2 or A2-configuration AR-15, since collectors and builders in that space specifically want Colt-marked factory parts rather than generic clones. It also shows up in restoration projects where an original rifle lost its correct furniture over the years and the owner wants to bring it back to factory-correct spec.

How does it compare to an adjustable stock setup?

A fixed A2 stock does not collapse or adjust for length of pull the way a carbine-length telescoping stock does, so length of pull is fixed to the stock's factory dimension. In exchange, the rifle-length buffer system this kit uses generally produces a smoother, softer recoil impulse than a carbine-length buffer system on the same caliber, because of the longer buffer travel. Builders choosing between the two are usually trading adjustability for that smoother cycling and, for retro builds, for historical accuracy.

What fits it?

This kit is built around mil-spec buffer tube dimensions, which fit standard AR-15/M16 mil-spec lower receivers. It does not include the lower receiver, upper, barrel, or bolt carrier group — those are separate purchases. Because it's a rifle-length system, it is intended for rifle-length gas systems, not pistol or carbine-length AR builds. A standard rifle-length action spring and buffer from any mil-spec-compliant maker will also work here if you ever need a replacement down the road.

Who is this not for?

If you're building a compact carbine or pistol-length AR, this rifle-length fixed stock kit is the wrong buffer system for that build — look for a carbine buffer tube and stock instead. It's also not the right choice if you want a length-of-pull-adjustable stock for multiple shooters sharing one rifle.

Does it work in California?

As a stock/buffer assembly rather than a receiver, this kit itself is not a regulated firearm part under California law, but what you build with it matters. Builders sometimes choose a fixed stock specifically as part of a California featureless-configuration build; confirm your complete rifle's configuration against current state rules before finishing any build, details on our California gun laws page.