I understand the differences between a commercial tube and mil spec tube, however, why do they produce a commercial tube, when there is already a mil-spec tube?

I mean it seems like having two systems that do exactly the same thing just as well as each other, like Blue ray and HD-DVD.
Why didn't commercial tubes go the way of the Beta-max?

The commercial tube is easier to manufacture, which in turn costs less and that's why we will always be plagued with them.

The better quality examples work fine but they require a commercial sized buttstock to work with them, which requires mfrs and dealers who bother, mfr/stock both commercial and milspec buttstocks.

I had an unsatisfactory experience with a commercial tube on my first build....out of spec O.D.
It was my ignorance of the two standards that lead me to a deal on a commercial buttstock kit.
I was sent another tube and the large, well-known AR mfr indicated that commercial specifications are not as stringent as milspec and variances occur.

I look at commercial as something you get stuck with, not something you choose.

cheaper to thread than to roll threads



 

Which ARs are sold with commercial spec as stock?
It seems like almost all the main Manufactuers come mil spec or they offer the same rifle with the commercial stock?
I guess it kind of baffles me on why someone would choose to ave a commercial tube on their gun?

It seems that most people prefer mil spec when it comes to stock and tubes.

Bottom feeders cutting corners to make a buck off of those who don't know better.

I don't think most people understand that it's the manufacturing process that dictates the tube diameter. The threaded hole in the back of the lower receiver is a fixed size, so in order to make a tube with threads that are the right diameter, the tube must be a certain diameter itself depending on how the threads are made. In a mil pec tube, the threads are rolled on and this process causes the threads to be raised up from the tube diameter. So, a narrower tube for a given thread requirement. A commercial tube on the other hand has the threads cut into the tube, so the tube must be made to the same diameter is the threading diameter requirements. That's where the difference in dimensions comes from. And yes, it's cheaper to cut threads than to roll them.

It's funny because some hobbygunner on another site is arguing that the commercial tube is stronger because it has thicker walls.

Comm tubes are 6061 Alum...cheaper to produce..thats why.

Some "Mil-Spec" ones are 6061 also.

The spec calls for 7075 T6 so the ones you are talking about are not mil-spec but someone trying to pass their product as such.

As to the original question. They make commercial receiver extensions because gun people are some of the cheapest folks on the planet, they rival the flea market crowd.

Hence the quotation marks.  Mil-Spec is a term thrown around so loosely.

Just throwing it out there, as a guy who makes threaded parts for a living...

I can make the rest of a part whatever diameter I want, and still cut threads to a certain pitch and major. It isn't blacksmithing. I can program tooling to do whatever needs to be done.

As for rolling threads...  I don't do it, but I can't see what costs more about it.
Tooling?  Sure. Not a recurring expense.

A real milspec is forged 7075, rolled threads, etc.
I believe it was Bushampster that came up with the commercial spec (extruded, 6061, cut threads, etc) to try to cut costs.

Yes , thicker = stronger,giving the same material, and as stated above, the extra OD allows cutting of threads.Not all things mil-spec are better, they are just mil-spec. There is allways room for improvement.

Commercial spec were the only ones you could get for years..

In this case thicker is not stronger.
The only reason that they made it thicker, as mentioned above was to have some material to cut threads into.
And they didn't go thick enough because the commercial thread OD does not fully engage the threads in the receiver.
And they used a softer material.
You have to consider the wall thickness at the bottom of the cut threads and then factor in the softer, extruded 6061 material.

Thicker is not stronger when it comes to commercial buffer tubes.


The often abused term mil-spec has to be used in this case in order to differeniate from the commercial offering.




The commercial buffer tube is not an improvement. Its only reason for existence is lower manufacturing cost.
It eliminates the forging process, 7075 material and rolled, full diameter threads.

No one willfully chooses commercial spec.
You get stuck with it sometimes with a lower price point rifle or it's through ignorance if you choose to buy a commercial buttstock kit outright.
The latter is how I acquired my 1st commercial buffer tube, ignorance.

dupe