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4/18/2021 9:59:29 PM
Posted: 3/6/2015 6:59:42 AM EDT
My clone saga continues, now I need a buffer tube, but which one?  I know there is a diameter difference between the milspec and commercial, but that seems to be where the manufacturers seem to stop counting, because I see "milspec" marketed with 4 position, 5 position, and 6 position, just what IS the proper spec?  What do the actual US Military M4s ship with? 4, 5, or 6?
Link Posted: 3/6/2015 7:13:01 AM EDT
For what it's worth my issue colt M4 has a 4 position stock.
Link Posted: 3/6/2015 7:30:47 AM EDT
Ask them what spec it adheres to. Then look it up. Could be the anodizing, or sizing, or design, etc. Lots of military specifications.
Link Posted: 3/6/2015 7:37:20 AM EDT
It refers to the OD and length of the tube.  Milspec stocks wont fit commercial tubes and vise versa.
Link Posted: 3/6/2015 7:39:12 AM EDT
milspec just refers to how it's manufactured if I remember right.
I think milspec has raised threads and a thinner diameter and commercial is sunken threads and a wider diameter.
commercial is just made because it's cheaper to manufacture.
Link Posted: 3/6/2015 7:59:39 AM EDT
Link Posted: 3/6/2015 8:11:20 AM EDT
Link Posted: 3/6/2015 8:15:07 AM EDT
From Larue's website:

Link Posted: 3/6/2015 8:15:29 AM EDT
Mil spec is 1.148

Commercial is 1.168

Mil spec has rolled threads

Commercial has cut threads

Link Posted: 3/6/2015 8:30:03 AM EDT
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The amount of derp in that pic is funny

If both REs have the same tube ID, and both tubes have threads that are to spec as far as pitch diameter, major and minor diameter, then the wall thickness under the thread minor diameter is the same. If the comm. spec tube were to be machined with a sharp V thread profile vs. an ISO thread form then that would create a weakened area. The structural difference is the fact that the Mil. RE is forged and the comm. RE is machined from billet.
Link Posted: 3/6/2015 8:38:12 AM EDT
So many people didnt read the entire OP.  Such sad, many idiots.
Link Posted: 3/6/2015 8:57:05 AM EDT

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Quoted:


So many people didnt read the entire OP.  Such sad, many idiots.
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Link Posted: 3/6/2015 9:00:21 AM EDT
Aren't most commercial one's extruded? Very cheap to do but quite a bit weaker then a Mil spec one.
Link Posted: 3/6/2015 9:33:38 AM EDT
Some of these parts are being made in China now and they're all kinds of out of spec.  Even on the expensive rifles.

Link Posted: 3/6/2015 9:50:08 AM EDT
The threads are not rolled...



But yeah, 4 pos, 7075 T6 AL...


Link Posted: 3/6/2015 9:57:13 AM EDT
Diameter/slant.. already covered.



The asshole that thought of commercial tubes needs a beating.


Link Posted: 3/6/2015 10:03:13 AM EDT
There are lots of commercial tubes out there now without a slanted rear end.
Link Posted: 3/6/2015 10:12:00 AM EDT

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Quoted:


Diameter/slant.. already covered.



The asshole that thought of commercial tubes needs a beating.

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Yeah, I'm 95% sure it's cheaper to make a mil-spec tube than a commercial type tube, aside from the finishing process.



The anodizing and dry film on the inside of the tube can be difficult to get right, a reasonable chunk of change can be saved by skipping or skimping on the dry film.



 
Link Posted: 3/6/2015 11:01:04 AM EDT
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Quoted:
So many people didnt read the entire OP.  Such sad, many idiots.

 

I've been shaking my head at most of the responses.
Link Posted: 3/6/2015 1:55:21 PM EDT

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Quoted:
The amount of derp in that pic is funny



If both REs have the same tube ID, and both tubes have threads that are to spec as far as pitch diameter, major and minor diameter, then the wall thickness under the thread minor diameter is the same. If the comm. spec tube were to be machined with a sharp V thread profile vs. an ISO thread form then that would create a weakened area. The structural difference is the fact that the Mil. RE is forged and the comm. RE is machined from billet.
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Quoted:









The amount of derp in that pic is funny



If both REs have the same tube ID, and both tubes have threads that are to spec as far as pitch diameter, major and minor diameter, then the wall thickness under the thread minor diameter is the same. If the comm. spec tube were to be machined with a sharp V thread profile vs. an ISO thread form then that would create a weakened area. The structural difference is the fact that the Mil. RE is forged and the comm. RE is machined from billet.


I didn't read it just posted for illustration. Possible density of metal not actual thickness?



 
Link Posted: 3/6/2015 2:18:37 PM EDT


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Quoted:
I didn't read it just posted for illustration. Possible density of metal not actual thickness?


 
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Quoted:





Quoted:





The amount of derp in that pic is funny





If both REs have the same tube ID, and both tubes have threads that are to spec as far as pitch diameter, major and minor diameter, then the wall thickness under the thread minor diameter is the same. If the comm. spec tube were to be machined with a sharp V thread profile vs. an ISO thread form then that would create a weakened area. The structural difference is the fact that the Mil. RE is forged and the comm. RE is machined from billet.



I didn't read it just posted for illustration. Possible density of metal not actual thickness?


 
Most structural difference is actually going to be due to the use of 7075 AL vs 6061 AL.





6061 extrudes much easier than 7075, however I really doubt the cost effectiveness of using a 6061 extrusion vs a 7075 impact extrusion, a lot less material/machine time is wasted with the impact extrusion.



Edit:



Video of receiver extension impact extrusions being made







 
Link Posted: 3/6/2015 2:30:11 PM EDT
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Magpul has a commercial MOE stock?
Link Posted: 3/6/2015 2:36:18 PM EDT

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Quoted:
Magpul has a commercial MOE stock?
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Magpul has a commercial MOE stock?
Everybody should remove  ALL out of spec "commercial" buffer tubes, and crush them, right  now.

 
Never shoulda been produced, sheer buggery,  nearly  fuckin stupid as the LARGE PIN colts.
Link Posted: 3/6/2015 2:40:34 PM EDT
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Quoted:
Ask them what spec it adheres to. Then look it up. Could be the anodizing, or sizing, or design, etc. Lots of military specifications.
View Quote

Link Posted: 3/6/2015 3:47:48 PM EDT
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Quoted:


Magpul has a commercial MOE stock?
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Quoted:


Magpul has a commercial MOE stock?


most, if not all, of their stocks are sold in both sizes
Link Posted: 3/6/2015 4:08:56 PM EDT
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Quoted:
Everybody should remove  ALL out of spec "commercial" buffer tubes, and crush them, right  now.    Never shoulda been produced, sheer buggery,  nearly  fuckin stupid as the LARGE PIN colts.
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Quoted:
Quoted:


Magpul has a commercial MOE stock?
Everybody should remove  ALL out of spec "commercial" buffer tubes, and crush them, right  now.    Never shoulda been produced, sheer buggery,  nearly  fuckin stupid as the LARGE PIN colts.

I'm sure this has been beaten to death somewhere else but can you explain how this is an issue?  Will a commercial BT not withstand a butt-stroke to a noodle or is there more to it than that?
Link Posted: 3/6/2015 4:09:45 PM EDT
Has anyone ever broken a receiver tube commercial or mill spec?

I've seen the lower receivers break where the receiver tube attaches.
Link Posted: 3/6/2015 6:08:29 PM EDT
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Quoted:
Has anyone ever broken a receiver tube commercial or mill spec?

I've seen the lower receivers break where the receiver tube attaches.
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I've seen commercial spec tubes snap off during classes and competitions when the user had to mortar the rifle to clear a jam.
Link Posted: 3/6/2015 6:12:49 PM EDT
Screw the mil spec. I just want a 6 position, 7000 series, forged, rolled thread receiver extension.
Link Posted: 3/6/2015 10:46:21 PM EDT
Quoted:
My clone saga continues, now I need a buffer tube, but which one?  I know there is a diameter difference between the milspec and commercial, but that seems to be where the manufacturers seem to stop counting, because I see "milspec" marketed with 4 position, 5 position, and 6 position, just what IS the proper spec?  What do the actual US Military M4s ship with? 4, 5, or 6?
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US Military Colt M4s ship with 4 position tubes.
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