So why did a commercial / milspec buffer tube ever come to be? Why not just stick with one or the other? Always seemed odd to me for such a benign part to have such differences instead of a simple common part.

Chris

Good question that I’d be interested in seeing the (knowledgeable) answer to, but I would bet it dates back to when a “civilian” company started making them and it was before everyone and his dog owned or was making ARs.

I always heard that the commercial tubes were cheaper to manufacture, less steps machining or something.

My understanding is that the tube is oversized so they could cheaply cut the threads into it.

quote:

Originally posted by Voshterkoff:
My understanding is that the tube is oversized so they could cheaply cut the threads into it.

This.

Both tubes have the same diameter at the threaded portion.

On a commercial tube the tube body is the same diameter as the threaded portion. On a mil-spec sized tube, the tube body is smaller in diameter than the threaded portion.

Real mil-spec tubes are made from 7075 forged aluminum. Though some mil-spec sized tubes are made from 6061 aluminum. Armalite made ARs with mil-spec sized tubes but out of cheaper extruded 6061 aluminum. Not sure if they still do. But they did.

Most, if not all, commercial sized tubes are made from extruded 6061 aluminum.

Some people say a true mil-spec tube is stronger than a commercial sized tube. Maybe it is, but I'm not sure it is. A commercial sized tube has a greater outside diameter than a mil-spec tube, while having the same inside diameter. So commercial sized tubes have thicker walls. I've seen both beat up and butt slammed to dislodge a stuck bolt and both held up.

7075 forged mil-spec tubes are probably stronger than mil-spec-sized tubes made of 6061 extruded aluminum, since they both have the same dimensions.

From what I remember the commercial tubes came from the 1980s aftermarket scene. Back then there was only a few players that sold their aftermarket AR parts in Shotgun News fairly cheap. Keep in mind you could buy a new Colt AR for around $425 in the mid 1980s, if I remember right.

Since the alloy 7075 is in the unweldable category or not recommended how would you do the plug on the end of a buffer tube for cheap? Their answer seemed to be.. go to cheaper and about 65 percent weaker alloy 6061 and weld the plug in. Impact extrusion (big dollar machines) was only something the little guys could only dream about back in those days.

Because: