Difference between "Commercial" and "MilSpec" parts??

[whitbaby]

It's hell to be stupid but what's the difference between "Commercial" and "MilSpec" parts??

[pick-me]

[ChunkyMonkey]

Mostly, they are referred to size spec.
Milspec is based on US Military Standard, and commercial is every thing else that is not US mil spec size or material.

[J]

The only time you really hear milspec vs commercial is in buffer tubes/stocks. Otherwise it is milspec or not milspec. To be milspec, it has to be made to the exact published standards for all parts sold to the US military. Milspec doesn't necessarily mean better. It could be better than a non-milspec piece if the non-milspec piece is made to lower standards than required by the military. But it could also be equal or worse to a non-milspec piece if it is made with better materials or processes or tolerances than the military requires.

http://ar15.co.za/wp-content/uploads/2013/04/Mil-Spec-vs-Commercial-Buffer-Tubes.jpg

[crays]

For stocs/tubes, here's a decent illustration:

http://www.laruetactical.com/magpul-ctr-mil-spec-stock-670-015-670-016-670-017-670-048

ETA: Same as what J posted

[Irving]

That photo is confusing. Which two areas are being measured on each buffer tube? Is that inner and outer diameter?

[crays]

x-sec view is tube OD, other is OD of threads.

[J]

Its measuring OD.

The biggest difference is that in a commercial tube, the tube starts wider, and the main body is untouched, and has the thread grooves cut in to it. So the tube is the same diameter as the 'teeth' or 'high-points' of the threads. On the milspec tube, the entire tube is cut into the blank, so the main body has the diameter of the 'grooves' or 'low-points' in the threads.

In other words, look at the threads...
The commercial spec has the threads cut down and recessed in to the tube, the milspec has the threads protruding from the tube.

Comm-spec can be made cheaper, and lighter.

The mil-spec get slightly deeper threads and is slightly stronger.

That said, comm-spec tubes are still really dang strong if made well.

[Irving]

Okay thanks, that's what it looked like, but I had difficulty properly wording my question.

[theGinsue]

I moved this thread to GD as I think a lot of our members would nenefit from this discussion. I know I have (never saw the size specs before- just knew commercial stocks/buffer tubes were bigger).

[ChunkyMonkey]

I moved this thread to GD as I think a lot of our members would nenefit from this discussion. I know I have (never saw the size specs before- just knew commercial stocks/buffer tubes were bigger).

Yep and due to the size fact, I dont mind using commercial stock on both commercial or mil spec tube, if that helps OP.

[baglock1]

It is also worth clarifying that although the mil-spec is shown to be a 4-position and the commercial spec is 6 (i.e. the holes on the bottom side of the tube), 6 position tubes can be had in mil-spec diameters.

[Irving]

So commercial stocks can be used on both tubes? I assume mil-spec stocks only work on mil-spec tubes?

[Mazin]

Mil spec stocks only fit on mil spec tubes. I haven't tried a commercial stock on a mil spec tune but if image it would work but you might have a lot of rattle, as well as the possibility of some position missing.

[Circuits]

In reference to stocks, it's only about the tube diameter anymore. Most so-called "milspec" tubes are just the smaller diameter, and still use cut threads and the wrong alloy, and don't follow the milspec for heat treatment and finish.

True mil-spec is 7075T6, same as the lower and upper receivers, made from a forging, with rolled threads and milspec dry lube finish.

"mil-spec diameter", often incorrectly advertised as "mil-spec", uses an extrusion, cut threads, and whatever finish the maker thinks is inexpensive enough. They can be had in good old 6061 or 7075.

Most people just care that their stock body fits nice and snug, and there's nothing wrong with commercial tubes be they in the old big diameter or the "mil-spec diameter".